^t^-^n 



"* / 



O 



REPORTS 



TO THE 



LOCAL GOVERNMENT BOARD 



ON 



PUBLIC HEALTH AND MEDICAL 

SUBJECTS. 

{NEW SERIES No. 55.) 



Dr. J. M. Hamill's Report to the Local Govern- 
ment Board on the nutritive value of bread 
made from different varieties of wheat flour. 

[Food Reports^ No. 14.] 



Presented to both Houses of Parliament by Command of Mis Majesty 




LONDON: 

PUBLISHED BY HIS MAJESTY'S STATIONERY OFFICE. 

To be purchased, either directly or through any Bookseller, from 

WYMAN and SONS, Ltd., Fetter Lane, E.C., and 

32, Abingdon Street, S.W. ; or 

OLIVER and BOYD, Tweeddale Court, Edinburgh; or 

E. PONSONBY, Ltd., 116, Grafton Street, Dublin. 

printed by 

DARLING and SON, Ltd., Bacon Street, E. 

1911. 



[Cd. 5831.] Price 3d. Monograph 



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J 



REPORTS 

LOCAL GOVERNMENT BOARD 

ON 

PUBLIC HEALTH AND MEDICAL 

SUBJECTS. 

(NEW SERIES No. 55.) 



Dr. J. M. Hamill's Report to the Local Govern- 
ment Board on the nutritive value of bread 
made from different varieties of wheat flour. 

[Food Reports, No. 14.] 



Presented to both Houses of Parliament bv Command of His fflajesty 




LONDON: 

PUBLISHED BY HIS MAJESTY'S STATIONERY OFFICE. 

To be purchased, either directly or through any Bookseller, from 
WYMAN and SONS, Limited, Fetter Lane, E.C., and 

32, Abingdon Street, S.W. ; or 

OLIVER and BOYD, Tweeddale Court, Edinburgh; or 

E. PONSONBY, Ltd., 116, Grafton Stbeet, Dublin. 



printed by 

DARLING and SON, Ltd., Bacon Street, E. 

1911. 



[Cd. 5831.] Price U. 



<#1 



Food Reports, No. 14. 



% 



Dr. J. M. Hamill's Report to the Local Govern- 
ment Board on the nutritive value of bread 
made from different varieties of wheat flour. 



During recent months public attention has been directed 
to the composition of flours which have been produced by different 
methods of milling or have been subject to different degrees of 
" purification " or refinement, and the view that bread made from 
certain of these flours may possess many dietetic advantages has 
been brought into considerable prominence, notably by the Bread 
and Food Eeform League and in the Press. 

The considerations involved appeared to be important in their 
possible bearing upon questions of physical development and the 
public health, and the Board instructed me to prepare a report 
summarising the principal scientific and technical information at 
present available on these matters in order that they might be 
considered in their practical aspects. The references on pp. 51 to 
53 indicate the published works which have been principally con- 
sulted for this purpose,* while I have made use of information 
kindly supplied to me by millers, some of which had been obtained 
in course of a previous inquiry made for the Board on the bleaching 
of flour and the addition of so-called " improvers ' to flour t 
before the subject had attained its recent publicity. 

It will be convenient first to give a brief account of the different 
varieties of wheat flour produced at the present day; next to in- 
dicate the nature of the chief chemical and physiological evidence 
which is at present available as to the dietetic values of flours and 
bread made therefrom, and finally to make reference to the position 
in these respects of so-called "standard" flour and bread. It 
should be observed that the present report deals solely with flours 
which are all ■ i genuine ' ' in the sense that they have been obtained 
by mechanical methods of milling from the wheat grain, without 
chemical treatment or the addition of the foreign substances 
referred to in my previous report.! 

L_CLASSES OF WHEAT FLOUR. 

Structure of Wheat Grain. 

The wheat grain as it arrives at the mill is devoid of glumes 
and palese (chaff), which have been removed by thrashing and 

° The numbers in brackets throughout the text of this report relate to 
references given on pp. 51 to 53 to work done on this subject. 

f Reports on the bleaching of flour and the addition of so-called " improvers " 
to flour, &c, by Dr. J. M. Hamill, and Dr. G. W. Monier-Williams. {Food 
Reports. No. 12. Cd. 5613.) 

(20420—21.) Wt. 8090—88. 2500 & 85, 8/U. D & S. 



2 



remain behind with the straw. The grain is surrounded by a 
series of tough cellular envelopes forming the skin of the grain. 
Of these the outermost is the pericarp, composed of three layers — 
epi- meso- and endocarp respectively. Within the endocarp is 
the deeply coloured testa, spermoderm or episperm, to the inner 
side of which is a hyaline membrane the remains of the nucellus 
or perisperm. Inside the hyaline membrane is a layer of cells, 
rich in protein but free from starch, termed the aleurone layer. 
This forms the outer layer of the endosperm, the remainder of 
which forms the bulk of the wheat grain, and consists of large 
thin-walled parenchymatous cells packed with starch grains of 
various sizes. These cells also contain protein from which the 
gluten of dough is formed. At the base of the grain lies the 
embryo or germ covered externally by the testa and pericarp, and 
abutting internally on the endosperm. At the apex the surface of 
the grain is covered by fine hairs forming the so-called beard. A 
deep depression or groove, called the crease, runs longitudinally 
from the apex to the base of the grain. The appearances and 
relationship to one another of the various parts of the grain just 
described can be seen on reference to Figures 1 and 2. 



G y 




Fio. 1. — Longitudinal section through a wheat grain. For simplicity 
and clearness the crease is omitted, and the several parts of the grain are 
represented diagrammatically only. B pericarp with testa and nucellus 
forming the branny envelope of the grain; A aleurone cell layer of endo- 
sperm; E parenchymatous cells of endosperm; G embryo or germ. 




— - p 




BUI 




U.. € 



p-— 



Fig. 2. — Cross section through branny envelope and outer portion of the 
endosperm of the grain x 160. P pericarp, consisting of e epicarp, m meso- 
carp and d endocarp. E endosperm, consisting of a layer of aleurone cells 
and p parenchymatous cells; t testa, n nucellus. 

The envelope or skin formed by the pericarp and testa with the 
remains of the nncelhis forms, on an average, about 15 per cent, 
of the grain. The parenchymatous endosperm amounts to 80 per 
cent, or more of the grain, and the alenrone layer to about 3 or 
4 per cent, of the grain. Yery divergent opinions exist as to the 
proportion which the germ bears to the whole grain. Bessy 01 ' 
considers that the germ amounts to as much as 6 per cent, of the 
grain. Girard a2) has come to the conclusion that the germ varies 
from 1*16 to 1*5 per cent, of the grain. Millers and others who 
have paid attention to this point consider Girard's estimate to be 
the more accurate, and are generally of the opinion that the germ 
forms from 1*5 to 2 per cent, of the grain. The above proportions 
which the various parts bear to the whole grain are approximate 
only, and may vary considerably in different varieties of wheat. 
Obviously the ratio of the skin to the endosperm would be greater 
in small grains than in large grains. 

Milling. 

The object of milling is to break up the grain into fine particles 
so as to render possible its conversion into bread. The entire 
grain may be ground up more or less finely and used as such for 
bread-making. To this product the name of wholemeal is com- 
monly given. The use of this milling product was recommended 
by Dr. Sylvester Graham in America, and, in consequence, in 
that country wholemeal is known as Graham flour. A portion of 
the husk may be removed, when the resulting product is frequently 
known as fine meal) in the United States this product is inaccu- 
rately described as ** entire " wheat flour * Fine meal or " entire " 



* It is necessary in this report to make use of this term, although it is a 
misnomer, on account of its general use in the United States where the 
majority of recent experimental work on the nutritive values of flour and 
bread has been carried out. As will be shown later the variety of flour 
described in this country as " standard : ' flour belongs to the class of " entire- " 
wheat flours. 



20420 



A 2 



wheat flour varies very considerably in composition, according to 
the amount of the skin or outer envelope of the grain which has 
been removed from it. In fact any product intermediate between 
ordinary flour and whole meal, in respect of the outer envelope 
or branny contents, may be included in the class of " entire ' 
wheat flour. Ordinary white flour is obtained by the removal of 
as much of the outer envelope and cellulose portions of the grain 
as possible. In preparing such flour the ideal which the miller 
endeavours to attain is the production of a flour consisting, as 
nearly as possible, of the contents only of the parenchymatous 
cells of the endosperm, and to this end the whole of the compli- 
cated machinery of modern milling is contrived. In practice, 
however, perfect separation is never attained, and flour always 
contains other portions of the wheat grain to a greater or less 
extent. By modern methods of milling from 70 to 73 per cent, of 
ordinary white flour can be obtained from an average cleaned 
wheat. 

The products other than flour obtained in milling are termed 
offal in the trade. The chief of these are bran, consisting of the 
pericarp and aleurone layer with some adhering parenchymatous 
cells of the endosperm (floury particles) ; pollard, really bran in 
a finer state of division ; germ, or wheat embryo ; fluff or fibre, 
which consists largely of the cellulose walls of the parenchymatous 
endosperm cells ; and sharps or middlings* which are mixtures of 
finely divided branny particles, fluff and fibre, and fragments of 
germ. The extent to which the various offals are separated from 
one another depends largely on their market value. Commonly 
the germ is separated and sold as such, but in some cases where 
the demand for it is small, and its separation would prove unre- 
munerative, the germ may be allowed to mix with the rest of the 
offal. 

Half a century ago flour in this country was produced entirely 
by stone-milling. In this process the wheat is ground between 
stones arranged horizontally, the lower being usually stationary and 
the upper revolving. The opposing surfaces of the stones are 
grooved, and can be separated from one another to any desired ex- 
tent so as to enable the wheat to be crushed to any required degree 
of fineness. In " low grinding," as it is called, the stones are close 
together, and the wheat in its passage between them is reduced at 
once to meal. The product thus obtained is wholemeal. By the 
simple process of sifting this meal through meshes of different 
degrees of fineness a separation can be effected into bran, pollard, 
middlings and flour. The flour consists of particles which pass 
through a bolting cloth containing from about 70 to 100 meshes per 
linear inch. In this process flour is produced at practically one 
operation, and contains, in addition to the contents of the starchy 
endosperm, finely ground pari Lcles of bran, germ, and other portions 
of the wheat grain small enough to pass through the boiling cloth. 
The middlings in this process contain a considerable proportion of 

The term middlings is also applied to intermediate products obtained in the 
grinding of wheat to flour in stone- and roller-milling. 



the endosperm of the wheat which formerly went with the mid- 
dlings into the offal, and was used for animal food. Stone millers 
came to recognise that flour could be obtained by appropriate treat- 
ment from these particles of endosperm which possessed, from the 
baker's point of view, qualities superior to flour obtained directly 
by sifting' the wholemeal through bolting cloth. In consequence 
of this, " high grinding " (i.e., with mill stones further apart) was 
adopted, and resulted in the production of a larger proportion of 
middlings, which by further treatment were reduced to flour. 
Nowadays, millers who still adhere to the old-fashioned stone-mill- 
ing process may have, in addition, a roller-mill installation in 
which the middlings are treated and the flour recovered from the 
endosperm which they contain. Owing to the very great degree 
of attrition to which wheat is subjected on the stones, only the 
softer or mellower varieties of wheat with tough skins are suitable 
for grinding on stones. Hard foreign wmeats with brittle skins 
cannot be satisfactorily milled on stones, as the skin is pulverised 
in consequence of the great friction to which the grain is subjected, 
and satisfactory separation of the branny particles from the flour 
becomes impossible. Flours refined to different degrees may be 
obtained from stone-milled wheat by means of suitable separation, 
varying from wholemeal, which contains practically the whole of 
the wheat grain, to a flour comparatively free from admixture 
with branny particles. Ordinarily the degree of separation sought 
to be attained in stone-milling is not high, and contrasts with that 
which can be obtained in the more complicated process of roller- 
milling. 

The introduction of roller-milling rendered it possible to utilise 
any variety of wheat, since the grain in this process is not sub- 
jected to severe attrition, and pulverisation of the bran is avoided 
as far as possible. In roller-milling the wheat grain is reduced 
to flour in gradual stages (gradual reduction process), during 
which the offal is continually removed by sifting and by the use 
of air currents. In this way a more complete removal of branny 
and other undesired particles can be effected, and a greater yield 
of highly refined flour can be obtained than in stone-milling. 
E oiler-mill installations are complex in their arrangements, and 
vary as regards details in different mills. 

In describing the chief features of roller-milling, reference 
may first be made to the important cleaning and washing 
stage of milling which has developed as a result of using foreign 
wheats with brittle skins ; these wheats often contain a consider- 
able amount of dirt and other extraneous matter which it is 
desirable to remove before the wheat is subjected to actual 
milling. The washing and drying processes are important for 
other reasons than the mere cleaning of the wheat, particularly 
for what is known as " conditioning." The branny coat of many 
wheats is brittle, and on milling would tend to break up into 
fine particles, which could only be separated with difficulty, if 
at all, from the flour. Moistening toughens the bran and pre- 
vents this occurring, and at the same time favourably affects 
the consistency of certain wheats so as to render them more 



easily milled. Excess of moisture, on the other hand, is in- 
jurious to the Hour, and for this reason judgment is required 
in carrying out this process of conditioning. After being cleaned 
and conditioned the wheat is ready for milling, and passes 
through a series of rollers, generally four in number, called 
break rollers. They are made of fluted chilled iron, and are run 
in pairs in the same direction at a differential speed. The clean 
wheat is allowed to pass continuously and successively through 
the series of break rollers, and in its passage the endosperm is 
gradually broken up and detached from the branny coat of the 
grain. The crushed product from each pair of rollers before 
passing to the next is sifted. The part which goes through the 
meshes of the sieve, commonly known as " throughs," consists 
generally of particles of endosperm of different sizes containing 
the germ admixed with a certain amount of branny fragments 
and other cellulose particles from the grain. The residue 
or " tails " from the last sieve is bran. The finest par- 
ticles of endosperm are removed from the " throughs " by sifting 
through silk meshes, and form what is known as " break flour." 
The larger particles of the " throughs " are graded according 
to size by passage over meshes of different sizes. The products 
thus obtained are termed coarse and fine semolina and coarse and 
fine middlings. They are alike in that they consist of fragments 
of endosperm and germ with adhering branny particles, and they 
differ chiefly in the size of the particles — middlings consisting 
of finer particles than semolina. These four products are now passed 
through machines termed " purifiers," which consist of a com- 
bination of a device for sifting with means for treating the semo- 
lina and middlings with air currents. In these purifiers the 
light branny and cellulose particles, fluff, &c. are removed by 
currents of air; the heavier particles pass through the meshes 
of the sieve, and the particles of intermediate gravity pass over 
the " tail " of the sieve and are removed as finished offal or are 
subjected to further treatment (i.e., passed on to reduction 
rollers) to obtain any floury endosperm which they may contain. 
The purified middlings and semolina, from which as much as 
possible of the branny and cellulose particles have been removed, 
pass to a series of reduction rollers, generally 12 to 20 in number. 
These are similar to the break rollers, except that they are 
smooth and are run at a less differential speed. The product 
from each pair of rollers, before passing to the next, is led 
through a sifting or "dressing" machine called a "centri- 
fugal," where the flour produced by the previous rollers is sifted 
out. After a passage through the whole series of rollers and 
centrifugals the residue consists of cellulose remnants of the 
wheat grain practically free from flour; this passes into the offal. 

In roller-milling the production of Hour is a gradual operation. 
The break flour is in part, at any rate, dark in colour; it is soft 
and contains fine particles of offal and, from the baker's point 
of view, is low in quality. The flour obtained from the last 
few reduction rollers (bottom of the mill) also contains offal, and 
is poor in colour and baking qualities. This " reduction " Hour, 
as it is called, is mixed with the break flour. The flour obtained 



from the first lew reduction rollers (tup of the mill) is generally 
classed as high grade Hour, whilst that obtained from the 
remaining reduction rollers (bottom of the mill) and also from 
the break rollers (break flour) come under the category of low 
grade Hours. 

Here and elsewhere when the text requires it, such terms as 
"high," "low," "good," or "poor," when applied to grade 
or quality, are used in the trade sense, and not in reference to 
food values. It may here be noted that, contrary to common 
notions, high grade flour is subjected to less grinding and coarser 
dressing than the lower grades which, in general, are dressed 
through very fine silk. Silk mesh, commonly varying from No. 9 
to No. 15, is used for flour dressing. No. 9 silk contains, approxi- 
mately, 96 meshes to the linear inch, and No. 15 about 150 meshes 
to the inch. The highest grade flours are dressed through the 
lower numbered silks and the low grade flours through the higher 
numbered silks. No. 13 silk, containing 129 meshes to the inch, 
represents a moderately fine degree of dressing according to 
modern practice. 

Ordinarily, in roller-milling 70 per cent, or a little more of 
the cleaned wheat is obtained as flour. One of the aims of the 
miller is to obtain as much of this flour from the reduction rollers 
and as little from the break rollers as possible. In good milling 
as little as 10 per cent, of the whole flour may be obtained as 
break flour. Bran produced and removed on the system of break 
rollers usually amounts, together with pollards (i.e., smaller 
branny particles) to somewhat under 20 per cent, of the cleaned 
wheat. The finer offal, sharps and germ, amounting to about 
10 per cent, or more of the cleaned wheat, is removed during the 
process of purification and the reduction of the semolina and 
middlings to flour. 



The Quality and Grading of Flour. 

In grading flour no absolute limits exist, Ordinary white 
flour may be roughly and arbitrarily divided into ' whites ' 
or " patents " which is a high grade flour, and " households ' 
which is a lower grade. "Whites" or "patents' represent 
the flour from the first few reduction rollers, and may be 
taken as about 50 per cent, of the total output of flour; 
the remaining 50 per cent, of the flour, from the lower 
reduction rollers, may be taken as representing the household 
grade. The yield of either grade may be increased at the 
expense of the other; thus, patent grade flour commonly repre- 
sents 60 per cent, of the total output of flour. Patent grade 
flour is the whitest that is obtained from the mill.* It presents 
a uniform appearance and is practically free from visible par- 
ticles of offal or other foreign substances; owing to the hardness 

* This is independent of the practice of artificial bleaching adopted by some 
millers, and referred to in my previous report. (See footnote f , p. 1.) 



8 

and granularity of its particles it does not stick together and 
become lumpy on being stirred with the hand, as is the case with 
the lower grades, but remains loose and " lively," as millers term 
it. Its baking qualities are also better than those of " house- 
holds ' ' flour and it commands a higher price than the latter. 
Household flour is softer and darker in colour than patent flour, 
owing to admixture with minute particles of offal ; the depth of 
the colour varies according to the part of the mill from which the 
flour has been derived, and depends upon the amount of offal 
which it contains. Minute particles of offal may be seen scattered 
throughout the flour, interfering with the uniform appearance 
which is characteristic of the highest grades. When the whole of 
the flour produced in a mill, with the possible exception of 2 or 
3 per cent, of the lowest grade, is mixed together, the mixture 
js known as a " straight-run " or " straight-grade " flour. A 
straight-run flour is intermediate in quality between patent and 
household grades. A variety of different grades of flour can be 
made to suit any demand by mixing the above grades in the 
required proportions, or by dividing the output of the mill in any 
desired way as it is being produced. 

Fate of the Germ in Stone- and Roller-Mill Processes. — Qu 
account of the importance which has come to be attached to the 
germ, it is convenient to consider it apart from the other products 
of milling. Curiously enough a considerable degree of uncer- 
tainty prevails amongst millers on this subject. In stone-milling 
it is probable that the germ is, wholly or partly, crushed into 
fragments between the stones, some of these fragments being- 
squeezed flat and ground to powder. There seems to be no 
doubt, however, that much of the germ passes away in the offal, 
the smaller fragments only passing with the flour through the 
coarse mesh which is customarily employed for dressing stone- 
milled flour. 

In roller-milling a certain amount of germ is probably removed 
in the preliminary processes of cleaning and washing to which 
the wheat is subjected. In the passage of the grain through 
the break rollers the germ is broken up into fragments which pass 
with the semolina and middlings to the reduction rollers. In 
passage through these rollers the germ becomes flattened and 
discdike, and, therefore, cannot pass with the flour through the 
silk of the centrifugal but is removed with the offal. Owing to 
the squeezing rather than grinding action of the rollers on the 
germ, it is probable that very little of the germ is reduced to such 
a fine state of division as to allow it to pass with the flour through 
silks of the fineness used in modern milling for dressing flour. 
Roller-milled flour may, therefore, be considered as practically 
free from germ. 

The germ, after having been rolled flat, passes away with the 
rest of the offal. In circumstances referrecl to above (see p. 4), 
the germ may be separated from the rest of the offal by sifting. 
This separation, however, is not complete; some of the germ is 
always left in the offal. The amount of germ which in this way 
can be recovered varies considerably in different mills. In some 



cases the amount of germ extracted from the offal amounts to no 
more than 0*3 per cent, of the cleaned wheat, in other cases to 1 per 
cent, or more. 

Millers generally are averse to returning the germ to Hour. 
They state that the presence of germ has a prejudicial effect upon 
the baking qualities of flour, that the stability and strength of the 
dough is adversely affected, and that it is impossible to produce a 
large well-risen loaf from flour containing germ. They state, 
also, that flour to which germ has been added is unsuitable for 
use with aerating substances, such as caking powder, on account 
of the unpleasant flavour developed by the action of the chemicals 
upon the germ. It is also maintained that the keeping qualities 
of flour are unfavourably affected by the presence of germ, and 
that flour containing germ soon acquires a rancid flavour. 

The statement of millers that the presence of germ in flour 
adversely affects its keeping qualities cannot be regarded as defi- 
nitely settled. Up to the present millers have not given much 
attention to this point, and in many cases have been content to 
infer that the superior "keeping qualities of modern roller-milled 
flour, as compared with stone-milled flour of former times, are 
due to the difference in the germ content of the two kinds of flour. 
It is more probable that the superior keeping qualities of modern 
flour are due to improved methods of milling and the use of sound 
wheats. In former days, when English wheat was largely used, 
sprouted grain and grain containing excessive amounts of 
moisture were common. Flour prepared from such wheats could 
not be expected to keep well. Modern stone-milled flour, when 
carefully prepared from sound wheat, keeps satisfactorily, and 
certain millers who have recently experimented in returning 
the germ to flour are of opinion that so long as flour does 
not contain an excessive amount of moisture its keeping qualities 
are not impaired by the presence of the germ. Raw germ 
can be ground to fine powder, and when mixed with flour to 
the extent of 2 per cent, makes no appreciable alteration in 
the colour of the flour. From the baker's point of view germ 
affects adversely, to some extent, the strength and stability of the 
dough. On the other hand, the presence of germ in flour, in 
amounts quite insufficient to affect the colour of the bread, im- 
parts what is commonly regarded as a pleasant nutty flavour to 
the bread. 

Many fancy flours prepared by the addition of nutritive sub- 
stances of various kinds to flour are on the market. Of these 
an important class are the " germ flours," prepared with the 
object of increasing the protein content of flour, and generally 
sold under fancy names. They consist of ordinary flour to which 
a preparation of germ, separated from the wheat in the roller- 
mill process, has been added; such flour may contain as much 
as 25 per cent, of germ. The germ before being mixed with 
the flour is subjected to heat in order to destroy its enzymic 
activity and to prevent any possibility of the development of 
rancidity in the flour. 



10 



A Comparison between Stone- and Roller-Mill Products, 

Ordinary stone-inilled Hour, dressed out from the wholemeal, 
corresponds most nearly to break flour in roller-milling. One of 
the objects in roller-milling is to keep the proportion of break 
Hour to total flour as small as possible. In stone-milling the 
flour is rather coarsely dressed, commonly through cloth con- 
taining 70 to 100 meshes to the linear inch. In modern roller- 
milling 130 meshes to the inch represents a dressing of moderate 
fineness. The higher grade roller-milled flours are produced 
with less milling, and are dressed through coarser silk than the 
lower grades. 

In roller-milling it is usual to obtain 70 per cent, or a little more 
of the cleaned wheat as ordinary white flour. In stone-milling, in 
spite of the loss of a certain amount of flour in the form of endo- 
sperm which formerly passed into the middlings and was rejected 
as offal, from 75 to 80 per cent, of the grain could be obtained as 
flour owing to the inclusion of finely divided particles of offal in the 
flour. Nowadays, the middlings may be ground on reduction 
rolls and the flour recovered from them, and either sold separately 
or be added to the stone-milled flour. There is no doubt that 
in the past a considerable proportion of foreign matter, in the 
form of dirt, millstone grit, &c, found its way into stone- 
milled flour. At the present time more attention is paid to the 
preliminary cleaning of the wheat than formerly, but the clean- 
ing equipment of stone-mills is usually not so complete as that of 
roller-mills. 

Reference has already been made to the germ-content of both 
stone- and roller-milled flour. The germ finds its way into most 
stone-milled flour, though not necessarily in large amount. Cer- 
tainly very much less, if any at all, is present in roller-milled flour. 

As regards baking qualities, the highest grades of roller-milled 
flour absorb more water, produce a larger loaf with a better colour 
and appearance, as judged from the usual criteria applied by the 
baker and the public, than the lower grades of roller-milled flour, 
and judged by the same criteria both are superior to stone-milled 
flour. It should, however, be said that those who use stone- 
milled flour, e.g., for home baking, would not ordinarily aim at 
producing loaves of the same appearance and volume as those 
which are made from highly refined roller-milled flour. 

# As regards flavour, bread from stone-milled flour is often con- 
sidered superior to that made from roller-milled flour. This is 
probably due to the fact that English wheat, which possesses a 
good flavour, is largely used in stone-milling, and also to the 
fact that a certain amount of germ is ground up in stone-milling 
and becomes mixed with the flour. In consequence, slight but 
subtle chemical changes due to enzyme action occur which result 
in the production of small amounts of flavouring material. Such 
changes would be favoured by the heat developed in grinding 



11 

and also by the fact that formerly the wholemeal was often col- 
lected in bags whilst warm and kept for some time before flour 
was dressed out of it. Loss of flavour in bread made from both 
stone- and roller-milled Hour is, however, frequently ascribed to 
what is termed " overproving." The baker in his concern to 
obtain as large a loaf as possible from his dough, allows the 
fermentative or raising- processes to proceed too far. A loaf in 
which the yeast fermentation has been excessive is said to be 
" overproved," and such a loaf not only lacks flavour but does 
not retain its moisture and softness, and soon becomes harsh 
and dry. 

In both stone- and roller-milling it is possible, in the case of 
an average wheat, to obtain a yield of Hour representing anything* 
between 70 and 100 per cent, of the wheat milled according to 
the amount of oifal allowed to pass into the Hour. As a rule, the 
greater the amount of oifal in the flour, i.e., the greater the 
percentage yield of flour obtained from the wheat, the darker is 
the loaf which it will produce. The colour of the loaf, however, 
depends not only upon the amount of oflal which the flour con- 
tains but upon the milling process adopted (stone- or roller- 
milling), and upon the colour of the wheat used (red or white). 
Eor these reasons different flours containing the same percentage 
(above TO per cent.) of the total wheat may yield loaves varying 
very considerably in colour. 

Although stone-milled flour is still made and there is a distinct 
though limited demand for it, it should be understood that the 
great bulk of the flour used in this country has been obtained 
by the more complicated process of roller-milling, whereby the 
more complete removal of branny particles is effected, and a 
greater yield of commercially high grade flour can be obtained. 
It is also possible by suitable adjustments to obtain from roller- 
mills a flour very similar in character to that produced by stone- 
mills. 

It will be convenient at this stage to summarise briefly the 
classes of milling products from which bread may be made : — 

(1.) Wholemeal or " Graham " flour is produced by grinding 
the entire wheat grain. It should, therefore, contain the same 
substances in the same proportions as the wheat grain itself. 
No sieves or bolting-cloths are employed in its manufacture, and 
particles of bran in the flour are obvious. It should contain 
practically the whole of the germ. 

(2.) "Entire" tvheat flour or fine meal is a product obtained 
by removing a portion of the bran and finely grinding the rest 
of the grain. " Entire " wheat flour can also be prepared from 
wholemeal, obtained by grinding between stones ; a portion of 
the branny particles is removed by sifting, and the resulting 
product is fine meal or " entire " wheat flour. The amount of 
oflal removed may vary greatly in different samples of flour of this 
class. The texture of this flour is somewhat coarser than that of 



12 

ordinary Hour; its appearance and characters will vary according* 
to the amount of offal which has been removed from it and the 
variety of wheat from which it has been milled. It includes so- 
called "standard" flour to which further reference is made below 
(p. 40). " Entire " wheat flour contains a portion of the germ, 
the amount depending upon the degree of fineness to which the 
flour has been dressed and the amount of offal which has been 
extracted. " Entire " wheat flour can be prepared either by 
stone- or roller-milling. When much of the offal is removed after 
grinding wheat on stones, a comparatively white flour is obtained 
which is commonly sold as stone-milled flour. It differs from 
ordinary roller-milled flour chiefly in containing a larger propor- 
tion of branny offal and germ. The colour of bread made from, an 
"entire" wheat flour depends not only on the amount of offal 
which the flour contains but upon the milling processes adopted 
(stone- or roller-milling) and upon the colour of the wheat used 
(red or white). For these reasons different " entire " wheat 
flours, containing the same percentage of the whole wheat, may 
yield loaves varying very considerably in colour. 

(3.) Households grade of flour is the commercially lower grade 
of flour obtained from roller-mills. It is darkish in colour, con- 
tains a small amount of very fine particles of bran, and, from 
the baker's point of view, is inferior to high grade flour for 
bread making. The terms " baker's grade " and " clear grade " 
are applied to similar lower grade flours in America. 

(4.) Patent grade flour is the commercially higher grade flour 
produced by roller-mills. It has a better colour and is freer 
from particles of offal than any other grade of flour produced in 
the mill. It possesses certain qualities specially esteemed by 
millers and bakers. The water-absorbing capacity of such flour 
and also the size and general appearance of loaves made from it 
appeal strongly to bakers. Whereas a certain grade of flour may 
yield only 90 quartern loaves per sack of flour (280 lbs.), as much as 
100 loaves may be obtained from higher grades as a result of 
the absorption of more water. The relative quality of house- 
holds and patent grades will naturally vary according to the 
amount of each grade which is milled. 

(5.) Straight-run or straight-grade flour is the whole of the 
flour produced in the roller-mill. It is intermediate in appearance 
and baking qualities between households and patent grades. 

(6.) Special flours may be prepared from any of the above 
varieties of flour, usually with the object of improving their nutri- 
tive qualities. They are generally sold under fancy names. Some 
of these flours contain bran ground to a very fine powder or other- 
wise treated ; others may contain such substances as lentil flour or 
banana meal. An important class of these special flours are the 
so-called " germ fours " in which powdered germ (usually cooked) 
is incorporated with one or other of the above grades of flour, the 
resulting product containing considerably more germ than any 
natural wheat flour. 



13 



II.— NUTRITIVE VALUES OF VARIOUS MILLING PRO- 
DUCTS (MEALS AND FLOURS) AND BREAD MADE 
THEREFROM. 

Under this heading it will be convenient first to refer to some 
of the principal data relating to the chemical composition of flour 
and bread, and next to physiological considerations which also have 
to be taken into account in considering food values. These 
questions have been investigated experimentally in the United 
States more fully than elsewhere and the information available is 
mainly obtained from the publications of the United States Depart- 
ment of Agriculture. 

Chemical Composition of Wheat and Flour. 

The mean composition of numerous samples of wheat exhibited 
at the Columbian Exhibition in 1893 is given in the following 
table : — 

Table l. (44) 

Grams. 
Weight of 100 grains of wheat ... ... ... 3'8T 



Moisture 

Proteins 

Ether extract (oil, &c.) 

Crude fibre 

Ash 



Per cent, 
1062 

1223 

ITT 

2-36 
1-82 



Carbohydrate (other than fibre) ... ... Tl"18 

The United States Department of Agriculture have collated 
a large number of analyses of wheat grown in different parts of 
the world, which show well the variation in composition of wheat 
from various sources. ° 3) From these analyses it would appear 
that wheat may contain as little as T per cent, and as much as 
14 per cent, or more of water. The protein content may vary 
from 8 to IT per cent., and the dry gluten from 2 to 14 per cent. ; 
the carbohydrates (excluding fibre) from 65 to 76 per cent. The 
ether extracts show variations from 0'28 per cent, to 2' 5 per 
cent, and the ash fluctuates between 1*4 and 2" 3 per cent. These 
differences in composition depended largely upon the varieties of 
wheat and upon climatic and other conditions under which they 
were grown. Flour obtained from these wheats would, of course, 
show variations in composition depending on the composition of 
the wheat from which it was derived. The importance of making 
comparison of the composition of different grades of flour only 
when these flours have been obtained from the same wheat is 
illustrated by the values obtained on analysis of milling products 
derived from the same and different wheats. 

In a number of different samples of straight-run flour the pro- 
portion of protein in some samples may be higher and in others 



14 

lower than in " entire ' wheat flours or wholemeal (Graham) 
flour. That these differences in the protein content of different 
samples of flour are due to variations in the composition of the 
wheat from which the various flours were ground will he obvious 
on reference to Table 2 : — 

Table 2. m 
Composition and Heat of Combustion of Wheats and Flours. 



Wheats and their 
Milling products. 



Protein.* 



Water. 



(NX6-5). 



(NX5-7) 



Fat. 



Carbohydrates 
when protein is 
estimated as : — 



(Nx6-25).|(Nx5-7). 



Ash. 



Heat of 
combustion 
per gram. 



Calcu- j Deter- 
lated. I mined. 



A. Oregon wheat ... 
Graham (whole- 
meal) flour from 
A. 

" Entire " wheat 
flour from A. 

{Straight - grade 
flour from A. 

B. Oklahoma wheat 
Graham (whole- 
meal) flour from 
B. 

" Entire " wheat 
flour from B. 

Straight - grade 
flour from B. 

Germ 



per- 
cent. 
8-99 
8-15 


per 

cent. 

9-12 

8-97 


per 

cent. 
8-32 
8-18 


per 
cent. 
1-83 
1-68 


per 
cent. 
78-30 
79-48 


per 
cent. 
79-10 

80-27 


per 
cent. 
1-76 
1-72 


Calories. 
3-997 
4-023 


8-66 


8-25 


7-52 


1-67 


80-35 


81-08 


1-07 


4-016 


8-94 


7-55 


6-90 


1-25 


81-82 


82-47 


0-44 


3-998 


8-65 
7-73 


16-82 
16-81 


15-33 
15-33 


1-83 
1-79 


71-38 
72-35 


72-87 
73-83 


1-32 
1-32 


4-160 
4-196 


7-46 


16-63 


15-16 


1-64 


73-05 


74-52 


1-22 


4*201 


9-93 


15-06 


13-74 


0-92 


73-57 


74-89 


0-52 


4-065 


8-73 


29-88 


27-24 


11-23 


45-45 


48-09 


4-71 


4-716 



Calorie?. 
4-008 
3-990 



3-900 
3-880 

4-110 

4-178 

4-159 
4-040 

4-597 



* In the above table the protein in addition to being expressed as N X 6*5 is also calculated on the 
basis of N X 5-7, since it has been found that this gives for wheat a result nearer to the truth than 
does the factor 6'25 commonly used for food stuffs. Accordingly, in most of the succeeding tables, 
the factor 5-7 has been used in calculating the protein from the nitrogen determinations. 



The straight-grade flour in this table was practically a straight- 
run flour, and amounted to 70 per cent, of the cleaned wheat. 
For a description of Graham and " entire " wheat flour, see 
pp. 3 and 11 of this report. 

On comparing the flours obtained from the two wheats in this 
table, it will be seen that they are alike in that their protein 
content progressively decreases from wholemeal (Graham) to 
straight-grade (straight-run) flour in the case of each wheat, but 
that the straight-grade flour from Oklahoma wheat contains 
much more protein than either "entire" wheat flour or whole- 
meal (Graham) flour from Oregon wheat. 

A number of determinations have been made in the United 
States of the composition of different varieties and grades of flour 
obtained from different wheats. In Tables 3 and 4 are set forth 
the results which hove boon obtained in the case of different mill- 



15 



ing products prepared from two samples of hard Scotch Fife 
spring wheat. 



Table 3. 



(83) 















Heat of 














combus- 


Milling Products. 


Water. 


Protein 
(N X 5-7). 


Fat. 


Carbo- 
hydrates. 


Ash. 


tion per 
gram. 

(deter- 














mined). 




per 


per 


per 


per 


per 






cent. 


cent. 


cent. 


cent. 


cent. 


Calories. 


Wheat (hard Scotch Fife 


10-41 


15-50 


2-28 


69-88 


1-93 


4-023 


spring wheat). 














Graham (wholemeal) flour 


13-21 


14-21 


2-01 


68-56 


2-01 


3-971 


" Entire " wheat flour ... 


13-51 


13-72 


1-69 


70-10 


0-98 


3-877 


Straight patent flour 


12-38 


13-60 


1-30 


72-04 


0-68 


3-861 


First patent flour 


1216 


13-31 


1-21 


72-93 


0-39 


3-960 


Second patent flour 


12-09 


13-05 


1-37 


7303 


0-46 


3-904 


First clear flour ... 


11-92 


17-73 


1-V8 


67-37 


1-00 


4-072 


Second clear flour 


10-40 


20-00 


3-17 


64-24 


2-19 


4-112 


"Red dog ''flour 


10-26 


21-83 


6-10 


57-72 


4-09 


4-430 


Middlings (Sharps or 


10-17 


18-64 


6-04 


59-72 


5-43 


4-314 


Shorts). 














Bran 


11-47 


17-10 


423 


59-89 


7-31 


4-187 



In this table first patent flour is a high grade flour, and may 
amount to about 56 per cent, of the cleaned wheat. It corresponds, 
roughly, to patent flour in this country. Second patent flour is the 
next lower grade of flour contained after the first patents have been 
removed. First clear grade or bakers' grade is obtained after the 
removal of the first and second patents, and represents about 
12 per cent, of the cleaned wheat. Second clear grade is 
obtained after the first and second patents and first clear grade 
has been removed; it amounts to about 5 per cent, of the cleaned 
wheat. " Eed dog " is a term applied to flour left after the 
above grades have been extracted. It is small in amount, and 
is only occasionally used for human food. Straight patent flour 
is practically a straight-run, and represents about 72 per cent, of 
the cleaned wheat. It includes first and second patents and first 
clear (bakers') grade. For a description of "entire" wheat 
flour, Graham flour, middlings (shorts or sharps), see pages 4 and 
11 of this report. 



16 



Table 4. 



C55) 



Composition and Heats of Combustion of Flours and other 
Milling Products of Wheat. 







t- 




02 
43 




Hj ' 


Heat of combustion 






*b 








2 S 

• r-t CC 


per gram. 


Milling product. 




X 




•73 




O 














"<i> £i 




O 


. 


ft 

0Q 


Calcu- 


Deter- 




eS 


O 


-p 

c3 


c3 


CO 


O 


lated. 


mined. 




* ! 


ft 


o 


< 


FM 








per 


per 


per 


per 


per 


per 








cent. 


cent. 


cent. 


cent. 


cent. 


cent. 


Calories. 


Calories. 


First patent flour ... 


10-55 


11-08 


1-15 


76-85 


0-37 


0-15 


3-989 


4-032 


Second patent flour 


10-49 


11-14 


1-20 


76-75 


0-42 


0-17 


3-992 


4-006 


Standard patent 


10-54 


11-99 


1-61 


75-36 


0-50 


0-20 


4-022 


4-050 


flour (straight run) 


















First clear grade 


10-13 


13-74 


2-20 


73-13 


0-80 


0-34 


4-087 


4-097 


flour. 


















Second clear grade 


10-08 


15-03 


3-77 


69-37 


1-75 


0-56 


4-153 


4-267 


flour. 


















" Red dog " flour 


9-17 


18-98 


7-00 


61-37 


3-48 


— 


4-349 


4-485 


(very low grade). 


















Shorts (sharps or 


8-73 


14-87 


6-37 


65-47 


4-56 


— 


4-219 


4-414 


middlings). 


















Bran 


9-99 


14-02 


4-39 


65-54 


6-06 


220 


3-9^8 


4-198 


" Entire " wheat 


10-81 


12-26 


2-24 


7367 


1-02 


0-54 


4-026 


4-032 


flour. 


















Graham flour (whole 


8-61 


12-65 


2-44 


71-58 


172 


0-71 


4-123 


4-148 


meal). 


















Hard Scotch Fife 


8-50 


12-65 


2-30 


7469 


1-80 


0-75 


4-114 


4-140 


spring wheat. 


















(ground in labor- 


















atory). 



















The terms applied to the various grades of flour in this table 
are denned below Table 3. Standard patent is synonymous with 
straight patent in Table 3. 

On comparing tables 3 and 4 it will be noticed that the 
protein contents of the two samples of wheat differ con- 
siderably, and that this difference persists with approximate 
parallelism in the various milling products obtained from the 
two wheats. A difference can be observed in the protein con- 
tent of each of the grades of flour, the more highly refined 
grades (" patents ") containing less protein than the lower grades * 
(" clears " and " red dog "). The straight-grade flour, as 
would be expected, is intermediate as regards its protein content 
between " patents " and low grade flour. It will be noticed also 
that the lower grade flours (" clears " and " red dog ") contain 
more protein than either " entire " wheat flour or Graham (whole 
meal) flour. In fact these low grade flours are richer in protein 
than any of the other milling products examined. A good 
example of the richness in protein of low grade flour compared 
with the higher grades is also furnished by the analyses in Table 14 
below. 



17 

If the three grades, straight-run (straight patent and standard 
patent), ' entire ' wheat, and Graham (wholemeal) flours, in 
Tables 3 and 4 be compared, it will be seen that Graham (whole- 
meal) flour is richest, and straight-run (straight patent and stan- 
dard patent) flour poorest, in protein, whilst " entire " wheat 
flour occupies an intermediate position. This relationship will 
also be observed on reference to Table 2. The differences, how- 
ever, which exist between these grades in respect of protein are 
commonly not large, and frequently no greater difference than about 
0*6 per cent, is to be observed between the protein content of 
straight-run flour and the wheat from which it is milled. (3fi) Con- 
versely, the carbohydrate content of milling products shows a 
tendency to decrease as the protein content increases. The fat 
content of flour is small, but is greater in the lower than in the 
higher grades. The ash varies in the same direction as the pro- 
tein, being greater in the lower than in the higher grades. So 
regular is this correspondence that the ash may be used as a guide 
in grading flour obtained from known wheats. (64)(55) 

When flour is made into bread a fresh complication is intro- 
duced depending upon the amount of water which the flour has 
absorbed, so that a flour relatively rich in protein may, as a result 
of absorbing more water, yield a bread containing less protein than 
bread derived from flour relatively poor in protein. The greater 
water-absorbing capacity of high grade flour (patents) should 
be remembered in this connection. 

In Tables 5, 6 and 7 are given analyses of bread made from 
flours whose composition is given in Tables 2, 3 and 4 respectively. 
These tables will serve to illustrate not only the variations in 
composition of bread made from different grades of flour from the 
same wheat, but also the greater differences which may exist 
between flours of the same grade obtained from different wheats. 



Table 5. 



(71) 



Composition and Heats of Combustion of Breads made from, Flours 

in Table 2. 



Bread made from — 


Water. 


Protein 
(NX6-25). 


Pat of 

dry 

flour. 


Carbo- 
hydrates. 


Ash. 


Heat of 
Combus- 
tion 
per gram. 




Per 


Per 


Per 


Per 


Per 






cent. 


cent. 


cent. 


cent. 


cent. 


Calories. 


Oregon straight - grade 


34-95 


541 


0-89 


57-85 


0-90 


2-765 


flour. 














Oregon " entire "-wheat 


3995 


5-70 


1-09 


52-39 


0-87 


2-566 


flour. 














Oregon Graham flour ... 


38-55 


6-11 


1-12 


52-68 


1-54 


2-562 


Oklahoma straight-grade 


37-65 


10-13 


0-64 


51-14 


0-44 


2-783 


flour. 














Oklahoma "entire "-wheat 


41-31 


10-60 


1-04 


46-11 


0-94 


2-714 


flour. 














Oklahoma Graham flour 


42-20 


10-65 


1-12 


44-58 


1-45 


2-516 



20420 



B 



18 



Table 6. (03) 
Com/position and Heats of Combustion of Breads made from Flours 

in Table 3. 















Heat of 














combus- 


Bread made from — 


Water. 


Protein 
(N X 5-7). 


Fat. 


Carbo- 
hydrates. 


Ash. 


tion per 
gram, 
(deter- 
mined). 




Per 


Per 


Per 


Per 


Per 






cent. 


cent. 


cent. 


cent. 


cent. 


Calories. 


Graham flour 


42-68 


9-54 


0-29 


46-10 


1-39 


2-495 


" Entire "-wheat flour ... 


40-97 


9-32 


0-19 


4875 


0-77 


2-535 


Straight patent (straight- 


38-77 


9-63 


0-04 


51-06 


0-50 


2-594 


run) flour. 














Do. do. 


37-37 


9-74 


0-26 


52-12 


0-51 


2-647 



Table 7. (57) 
Composition and Heats of Combustion of Breads made from Flours 

in Table 4. 







•25). 




OS 

QJ 

c3 
U 




Heat'of Combus- 
tion per gram. 


Bread, crumb, made 


u 


CX 




>> 






from — 








+3 


-P <A 


. 


rO 


. 


Deter- 


Calcu- 




c3 


O -s 


03 


p3 


00 


mined. 


lated. 




£ 


P4 


Pa 


Q 


< 








Per 


Per 


Per 


Per 


Per 


Calo- 


Calo- 




cent. 


cent. 


cent. 


cent. 


cent. 


ries. 


ries. 


First patent flour ... 


44-40 


7-48 


0-71 


47-14 


0-27 


2-384 


2-480 


Second patent flour 


42-10 


7-75 


0-72 


49-16 


0-27 


2-492 


2-581 


Standard patent floui: 


44-89 


7-58 


0-88 


46-35 


0-30 


2-417 


2-468 


(straight-run). 
















" Entire " - wheat 


49-16 


745 


1-14 


41-73 


0-52 


2-166 


2-291 


flour. 
















Graham (wholemeal) 


47-20 


7-76 


1-27 


42-82 


0-^5 


2-060 


2-367 


flour. 

















The energy which can be derived from flour and bread on com- 
bustion has a bearing on the question of food values, and can be 
stated in heat units (calories)* obtained by calorimetric observa- 
tions. One gram of starch on combustion yields 4,200 calories, 
one gram of vegetable protein yields 5,900 calories, and one gram 
of fat or oil yields 9,300 calories. The caloric value of flour is 
the sum of the caloric values of each of the above classes of 
substances which it contains. Since vegetable protein has a soine- 
what higher caloric value than starch, the flour with a high pro- 
tein content will, other things being equal, have a somewhat 
higher caloric value than flour poor in protein. The caloric value 
will also, of course, vary inversely as the water-content of the 
flour. The caloric values of different milling products are given 

* A caloric is the amount of heat required to raise one gram of water from 
0° to 1° C. The Caloriu (with the initial letter capital) is often aged to express 
one thousand calories, 



19 



in Tables 2, 3 and 4. In Tables 5, 6 and 7 are given the calorie 
values of bread made from the flour in Tables 2, 3 and 4 respec- 
tively. 

It will be observed that the caloric value of bread is approxi- 
mately five-eighths of the caloric value of the flour from which it is 
made. Other determinations of the composition and caloric value 
of flour and bread are given in various bulletins of the United 
States Department of Agriculture, Office of Experiment Stations, 
and also in Bulletin 13, Part IX., of the Division of Chemistry. 

The Germ. 

Analyses of this structure vary somewhat according to the degree 
to which it has been freed from adhering branny fragments and 
particles of flour. The following are analyses of germ in three 
different degrees of purity; the second analysis represents the 
purest germ. 

Table 8. ( ° 



Milling 
Product. 


Moisture. 


Ash. 


Ether- 
Extract 
(Fat etc.) 


Carbo- 
hydrates. 


I* rote in 
NX6-25. 


Nitrogen. 


Phos- 
phoric 
acid. 


Fibre. 




Per 


Per 


Per 


Per 


Per 


Per 


Per 


Per 




cent. 


cent. 


cent. 


cent. 


cent. 


cent. 


cent. 


cent. 


Germ 1 ... 


8-69 


3-42 


9-35 


53-28 


24-13 


3-86 


1-83 


1-23 


i, 2 ... 


8-75 


5-45 


15-61 


35-19 


33-25 


5-32 


2-57 


1-75 


n 3 ... 


7-68 


4-94 


13-75 


39-25 


32-88 


5-26 


2-56 


1-50 



An analysis of germ is also given in Table 2. It will be seen 
that about J of the germ consists of protein, J of carbohydrate, 
and -}■ of oil, the remaining J consisting of water and mineral 
matter. 

The inclusion of germ in flour raises its protein content. It has 
been shown in one case that the addition of 7 per cent, of finely 
ground germ to a straight grade flour containing 15'0G per cent, 
of protein resulted in a mixture containing 16'3 per cent of pro 
tein. (7o) In the experiment here referred to the addition of 7 per- 
cent, of germ was made on the assumption that this represents the 
amount removed in milling. I am informed, however, that the 
investigator who conducted the experiment has stated that the 
percentage added did not represent pure germ, but that mixed 
with the germ was a certain amount of adhering flour and offal 
which had not been removed. It is probable that wheat does 
not contain more than 2 per cent, of actual germ, so that on tin's 
basis, if the whole of the germ were included in the flour, the 
protein content of the flour would be raised by about 0*6 per cent 
In the milling of white flour the germ which can be recovered 
from the offal does not amount to more than about 1 per cent, of 
the whole wheat, and in many cases to not more than 0'5 per cent., 
and more than this could not be added to flour if it were desired 
solely to return the germ of which it had been deprived without 
at the same time adding branny offal. In this case the gain in 
protein would represent about 0"2 to 0*3 per cent. 



20420 



B 2 



20 



The special forms of flour referred to as " germ flour " on p. 9, 
may contain a large amount of protein as a result of the addition 
of germ. The additional protein so contributed may be as much as 
4 or 5 per cent. 

Nature of the Proteins of Wheat. 

The proteins of wheat include a globulin, an albumin and a 
proteose, together with giiadin and glutenin. In the presence of 
water the latter two substances unite to form gluten. The com- 
position of wheat proteins is given in the following table : — 

Table 9. (45) 
Composition of Wheat Proteins. 



Constituents. 


Carbon. 


Hydrogen. 


Nitrogen. 


Sulphur. 


Oxygen. 




Per cent. 


Per cent. 


Per cent. 


Per cent. 


Per cent. 


Globulin 


51-03 


6-85 


18-39 


0-69 23-04 


Albumin ... 


53-02 


6-84 


16-80 


1-28 ! 22-06 


Proteose 


51-86 


6-82 


17-32 


24-00 


Giiadin 


52-72 


6-86 


17-66 


1-14 21-62 


Glutenin ... 


52-34 


6-83 


17-49 


1-08 22-26 



The average amount of nitrogen in the protein of wheat is about 
176 per cent., and the proper factor, therefore, for computing the 
total protein matter from the percentage of nitrogen found by 
analysis is 5*68 instead of 6*25, the one usually employed in food 
analysis. (45) 

Osborne and Voorhees have found that wholemeal flour of 
samples of spring and winter wheat contains the above-mentioned 
proteins in the following proportions : — 

Table 10. (29) 

Spring Wheat. Winter Wheat. 

Per cent. Per cent. 

Glutenin 4'68 417 

Giiadin 396 390 

Globulin 062 0*63 

Albumin 039 036 

Proteose 021 043 

It is important, however, to note that the composition of the 
protein in the germ differs from that in the rest of the wheat 
grain. The embryo or germ itself contains no giiadin nor 
glutenin ; it contains 10 per cent, of albumin, 5 per cent, of 
globulin, and 3 per cent, of proteose. The embryo consists of 
nucleated cells, and therefore contains a considerable amount of 
nucleic acid which exists in combination with the albumin and 
globulin. Only a small quantity of this organic phosphorus- 
containing combination occurs in the entire seed, and this is found 
chiefly in the tissues of the embryo or germ rather than in the 
endosperm. 



21 



Mineral Matter (Phosphorus, fyc). 

The residue obtained on the incineration of wheat and flour is 
termed the " mineral matter " or " mineral content " of the wheat 
or flour in question. In the unburnt grain and flour some of the 
elements which appear in inorganic mineral form in the ash are 
in part, at any rate, combined organically with the constituents 
of the grain or flour. Thus the greater part of the phosphorus 
which appears as phosphate in the ash is present in the grain in 
organic combination in such compounds as nuclein, lecithin, and 
other phospho-organic compounds. (16) 

It has been shown that the greater part of the phosphorus in 
bran can be extracted with water and with dilute acid, and that 
the bulk of this phosphorus occurs in organic combination prob- 
ably in the form of a potassium-calcium-magnesium salt of a 
phospho-organic acid/ 3 ' This is probably identical with phytin 
— a phosphorus compound widely distributed in seeds (31) Phytin 
would appear to be a phosphoric acid ester of inosite. ( " 7; 

Similarly sulphur combined in the proteins of wheat and 
flour appears in the ash in inorganic form as sulphate. Iron also 
occurs in organic combination, and the same is probably true of 
other elements found in the ash. It should, therefore, be borne 
in mind that the term " mineral content " refers only to the 
residue left after incineration, and the combination in which the 
elements are found in the ash gives no indication of the form in 
which these elements were present in the wheat or flour. 

The total mineral content of wheat varies within wide limits. 
The analyses of a large number of samples of wheat gave values 
for the mineral content lying between 1*38 and 2 35 per cent, of the 
grain. C43) The mean mineral content of 227 samples was 1'81 per 
cent. The composition of the ash of mixed grades of Canadian and 
Argentine wheat are contrasted in the following table : — 



Table 11 



(46) 



Kind of Wheat. 


K 2 0. 


Na 2 0. 


CaO. 


MgO. 


Fe 2 3 . 


P=A. 


S0 3 . 


01. 


SiO,. 


Canadian 
Argentine 


Per 

cent. 
24-03 
14-06 


Per 

cent. 
9-55 
2 04 


Per 

cent. 
3-50 
5-73 


Per 

cent. 
1324 
16-88 


Per 

cent. 
052 
0*57 


Per 

cent. 

46-87 
58-38 


Per 

cent. 

o-oi 

0-02 


Per 

cent. 




Per 

cent. 
2-28 
2-32 



Most of the mineral matter in wheat is present in the outer 
coats of the grain, and in the milling of a 70 per cent, straight- 
run much less than half of the total mineral matter of the grain 
may be left in the flour. The distribution of mineral matter in 
the milling products obtained from a hard Scotch Fife spring 
wheat have been determined and are set out in the table below : — 



22 



Table 12. (54) 

Proportions of Total Weight of Wheat and of its Nitrogen and 

Ash Content Recovered in the Different Milling Products. 



Milling Products. 



Proportion 
of original 



Proportion of total 

nitrogen and ash 

in original wheat. 



wneat. 


Nitrogen. 


Ash. 


Per cent. 


Per cent. 


Per cent. 


72-6 


69-50 


20-23 


0-5 


0-60 


0-49 


1-9 


2-85 


3-67 


11-6 


13-70 


29-38 


13-4 


14-50 


45-12 


100-0 


101-15 


98-89 



Standard patent flour (straight- run) 
Second clear (low-grade flour) 
Red dog flour (very low-grade flour) 
Shorts (sharps or middlings) 
Brau 

Total 



The terms applied to the various milling products in this table 
are defined beneath Tables 3 and 4. 

It will be observed that only 20 per cent, of the mineral matter 
of the grain is present in the straight-run flour, whilst 74 per 
cent, is removed in the offal. The amount of ash present in 
different milling products can be seen on reference to Tables 2, 
3, 4, and 13. As already stated, the amount of ash differs 
somewhat in the products from different wheats, and varies in 
each product in the same direction as the protein content, being 
greater in the lower than in the higher grades of flour. It will 
be seen that the ash of Graham (wholemeal) flour is about four 
times as great as that of "patent" flour; the ash of "entire' 
wheat flour occupies an intermediate position. 

In the following table is given the total ash and also the 
percentage composition of the ash of a sample of medium hard 
winter wheat and of all the different grades of flour and other 
products obtained from the wheat. 100 parts of the wheat gave 
25 '8 parts of patent flour, 42 parts of so-called " straight " flour, 
3*87 parts of a low grade flour, and 23'8 parts of bran. 



Table 13. 



(05) 





Total 
Ash. 


In total Ash. 




Milling Products. 


Silica. 


Ferric 
Oxide. 


Potash. 


Lime. 


Mag- 
nesia 


Phos- 
phoric 
Acid. 


Sul- 
phur. 


Wheat 

Patent flour ... 
Straight flour 
Low grade flour 
Bran... 


Per 

cent 
1-62 
0-31 
0-40 
0-70 
5-25 


Per 

cent. 
1-04 
2-33 
1-28 
0-50 
097 


Per 

cent. 
0-27 
0-47 
0-26 
0-25 
0-27 


Per 

cent. 
29-70 
38-50 
36-31 
32-27 
28-19 


Per 
cent. 
3-10 
5-59 
5-65 
4-51 
2-50 


Per 

cent. 

13-23 
4-39 
6-44 
933 

14-76 


Per 

cent. 
52-14 
48-05 
49-32 
53-10 
52-81 


Per 
cent. 
0-13 
0-09 

o-io 

0-16 
0-21 



In tli is table 



grade of 



households ' 



straight ' flour would correspond to a high 
flour in this country. 



23 



In the above table some variation in composition, though in 
most respects not great, occurs in the different ashes. In all of 
them phosphoric acid forms, approximately, half of the total 
mineral matter; but the magnesium content fluctuates consider- 
ably, as also does the iron and silica which are present in small 
amounts only. In this and in Tables 3 and 4 it will be observed 
that the total ash of the so-called low grade flours is about twice 
as great as that of the high grade patent flour. 

The distribution of phosphorus and nitrogen in different 
milling products has also been studied, and the results obtained 
in the case of two varieties of wheat are given in the table 
below : — 

Table 14 . (ti5j 
Nitrogen and Phosphorus in Wheats and their Milling Products. 



Milling Products. 


Water. 


Phos- 
phorus. 


Nitrogen. 


Protein 
(N x G-25). 


St. Louis winter wheat : 


1 
Per cent. 1 Per cent. 


Per cent. 


Per cent. 


Whole wheat 


12-85 


0*262 


1-87 


11-7 


Royal patent flour ... 


13-37 


0-051 


1-39 


8-7 


Extra fancy flour (lower grade flour) 


12-51 


o-ioo 


1-78 


11-1 


Low-grade flour 


11-94 


o-ioo 


2-08 


13-0 


Middlings (shorts, sharps) 


11-21 


0-225 


2-73 


17-1 


Bran ... 


12-15 


0-828 


2-62 


16-4 


Minnesota spring wheat : 










Whole wheat 


11-09 


0-230 


2-24 


14-0 


Patent flour ... 


12-29 


0-050 


2-10 


13-1 


Bakers' grade flour ... 


12-14 


0-091 


2-40 


15-0 


Shorts (middlings, sharps)... 


11-27 


0-560 


2-78 


17-4 


Bran ... 


11-23 


0-330 


2-55 


15-9 



The term " extra fancy " in this table is applied to the flour 
left after the removal of the patent grades. The term " bakers' 
grade " is defined below table 3. 

It will be observed that the wheat grain may contain about 
5 times, and the bran about 16 times, as much phosphorus as au 
equal weight of the highest (patent) grade of flour. It will be 
noticed that the samples containing larger proportions of phos- 
phorus show also larger proportions of nitrogen . 

The amount of mineral matter in bread depends upon the 
mineral content of the flour from which it is made, but is also 
influenced by the quantity of water present in the bread and the 
addition of salt, potatoes, or other bread improvers during manu- 
facture. The hardness of the water and the mineral content of 
the yeast used also affect the mineral content of the finished bread 
to some extent. As may therefore be expected, the mineral content 
of bread bears no fixed relationship to that of the flour from which 
it has been made. In Tables 5, 6, and 7 are analyses of bread made 
from flours whose analyses are given in Tables 3, 4, and 5, re- 
spectively. It will be seen that the ash contents of the breads are 
very variable, relatively, to the ash contents of the flours from 
which they were made; in some cases there is slightly less than, 
and in others about half, the amount of mineral matter present 
in the original flours. 

From a number of analyses made in the United States, it 
appeared that the ash of bread made from patent flour amounted 



24 

on the average to 1*19 per cent, of the whole loaf. Ub) Of this, 
0'57 per cent, was common salt, so that the mineral matter in 
the bread, apart from salt, amounted to about 0'6 per cent. In 
the case of Graham (wholemeal) bread the ash content amounted 
to 1*59 per cent., of which 0'69 per cent, was salt; the mineral 
matter, apart from salt, thus amounted to 0'9 per cent. 

Greater differences, however, between bread made from Graham 
(wholemeal) flour and patent or even straight-run (straight-grade, 
straight patent, and standard patent) flour are shown in the analyses 
given in Tables 5, 6, and 7. It would appear probable that the 
ashes in these three tables do not include added salt, although 
this is not definitely stated in the publications in which these 
analyses occur, 

An actual baking experiment (51) was conducted with the fol- 
lowing ingredients : — 

Flour, 21,670 grams, containing 0'46 per cent, of ash. 
Potatoes, 1,050 „ ,, 0'80 

Sugar, 127 ,, — ,, ,, 

Yeast, 2,350 ,, ,, 1*55 ,, ,, 

Salt, 298 „ „ lOO'OO 

The yield of bread amounted to 29,840 grams, containing 
1'22 per cent, of ash and 35*56 per cent, of water. 

Physiological Considerations. 

" Digestible " Nutrients and Available Energy of Bread 
from Different Flours. 

The chemical data above given supply some indication of the 
general or gross food value of bread made from various flours. 
For example, they show that bread whether made from whole- 
meal, " entire " wheat, or patent flour is not merely a starchy 
food, as is sometimes popularly supposed, but contains in addi- 
tion a material quantity of nitrogenous constituents (proteins) 
which are essential to a diet capable of maintaining existence, 
in this respect contrasting with food such as arrowroot which 
consists almost entirely of starch. The analyses indicate also to 
some extent the differ ences which exist not only in bread made from 
flours which have undergone different degrees of refinement but 
also in bread prepared from the same grade of flour derived from 
different kinds of wheat. 

On a diet consisting entirely of bread an adequate intake 
of nitrogen could usually be ensured if the amount of bread 
consumed is sufficient to provide the necessary energy for the 
body. Two-and-a-half pounds of bread will furnish more than 
3,000 Calories, (4i,) which is a sufficient daily allowance for most 
purposes. (50) With a bread which contains as little as 7 per cent.*^ 
of protein (calculated as ~N x 5*7), the above allowance would 
provide an intake of about 14 grams of nitrogen for daily needs. 
It should be added, however, that in the opinion of some who have 
given attention to this question, a larger daily supply of nitrogen 
is desirable. Other things being equal, a diet which consists 
wholly of bread would possess greater advantages in these respects 
if the bread were made from " strong " wheats, which are usually 
i id) in protein. 

It is not, however, possible to base conclusions as to the nutri- 
tive value of different breads merely upon chemical data obtained 



25 

from analyses of the breads themselves or the flour from which 
they are made. For example, the protein value arrived at 
empirically from the nitrogen content of bread or flour gives no 
indication of the nutritive value of the nitrogenous substance!* 
present, and the same applies also to the "mineral matter" oi 
bread and flour. The degree to which bread is acted upon by the 
digestive juices, and the extent to which the products of digestion 
are absorbed and assimilated, also require elucidation. Numerous 
investigations have been undertaken with this object chiefly in 
the United States, and in Germany where much of the work 
done has had reference to rye-bread. In work of this kind in- 
volving the estimation of small differences, the necessity for 
eliminating as far as possible all disturbing factors introduces 
many difficulties and uncertainties. Nevertheless, valuable 
results have already been obtained, although much yet remains 
to be done. 

The action of the digestive enzymes on bread made from dif- 
ferent grades of flour has been studied in vitro, {m (59) and although 
the information which can be obtained in this case by such 
methods is limited and may not always be satisfactory, (53) the 
results would on the whole seem to indicate that patent grade 
flour is more easily acted upon by the digestive juices than either 
" entire " wheat flour or Graham ( wholemeal) flour. 

Useful information has been obtained as the result of actua] 
feeding experiments on man, carried out in the Experiment 
Stations of the United States Department of Agriculture, 
although they are perhaps open to criticism on account of the 
shortness of the period during which the observations were made. 
As they represent the principal work done in relation to " digesti- 
bility " of bread, it is necessary to refer to them at some length, 
and to incorporate in this report some of the principal tables pub- 
lished in this connection. 

In one series of experiments the digestibility* of bread made 
from " standard patent "t (straight-run) flour, " entire " wheat 



° A distinction should be drawn between actual digestibility and apparent 
digestibility. The actual digestibility of a food is represented by that portion 
which is actually absorbed from the alimentary canal into the body. Apparent 
digestibility is measured by the difference in the composition of the food taken 
and of the faeces excreted. A certain proportion, however, of the fasces 
is composed of material which has been absorbed and utilised in the body and 
re-excreted by way of the intestine (metabolic products). The determination 
of apparent digestibility is a comparatively easy matter. There is, however, at 
present no satisfactory means of distinguishing between undigested residue and 
metabolic products in the fasces so that the determination of actual digestibility 
is a difficult problem. In this report the term digestibility is used in the sense 
of apparent digestibility. In order to avoid confusion the use of the word 
" availability " (ausnutzbarkeit) has been suggested instead of the term apparent 
digestibility. It is scarcely necessary to add that the " digestibility " referred 
to here has no necessary relation to the production or prevention of 
" indigestion." 

In the American experiments of which an account is given in this section of 
my report no attempt was made to study the ease or rapidity of digestion of 
bread made from different sorts of flour. 

f In the United States the term " standard patent " is one amongst others 
which connote the grade of flour known in this country as " straight run," see 
p. 12 of this report. Precise descriptions of this and other terms applied to 
flour and referred to in this report are given beneath various tables throughout 
the report. 



26 



flour, and Graham (wholemeal) flour from the same wheat was 
investigated, and the proportion of protein and carbohydrate 
digested and the energy measured in Calories which were available 
from each bread were ascertained. From these data the digestible 
protein, carbohydrates and available energy were calculated for the 
Hours from which the breads were made. The results obtained are 
summarised in Table 15 : — 



Table 15 



(58) 



Proportions of Total and Digestible Nutrients and Available 
Energy in Different Grades of Hard Spring Wheat Flour. 



Grades of Flour from 
Hard Spring Wheat. 


Protein 
(JS X 5-7). 


Carbohydrates. 


Heat of Combustion 
(energy) per gram. 


Total. Digesti- 
ble. 


Total. 


Digesti- 
ble. 


Total. 


Available. 


Standard patent (straight- 
run) flour. 

" Entire " wheat flour ... 

Graham (wholemeal) 
flour. 


Per 

cent. 
11-99 

12-26 
12-65 


Per 

cent. 
10-2 

9-9 
9-8 


Per 

cent. 
75-36 

7367 

74-99 


Per 

cent. 

73-5 

69-3 
66-3 


Calories. 
4-050 

4-030 
4-150 


Calories. 
3-650 

3-445 
3-350 



For the definition of terms in this table, see beneath Tables 3 
and 4. 

From this table it will be observed that according to analysis 
Graham (wholemeal) flour contains the largest proportion of 
protein and the largest amount of energy, whilst the standard 
patent* (straight-run) flour contains the smallest proportion of 
protein but a little more energy than the " entire " wheat flour. 
According to the results of experiments on man, however, 
the proportions of " digestible " protein and the amount of 
energy actually available to the body were greater in the standard 
patent (straight-run) flour than in the " entire " wheat or Graham 
(wholemeal) flour. The latter contained the least digestible 
protein and available energy. No sensible difference in 
" digestibility "f between patent and straight-run flour could be 
observed. (52)(61)((i2) In order to ascertain whether the digestibility 
of a flour is in any way affected by its protein content, a sample 
of flour was diluted with 20 per cent, of wheaten starch prepared 
from the same flour, so that two flours of similar grade, differing 
only in protein content, were obtained. As a result of digestion 
experiments it was found that the presence of an excessive 
amount of starch in flour appeared to diminish the digestibility 
of the protein constituent of the flour. ((i0) This, if correct, 
would have a bearing upon the nutritive value of flour made 
from wheats containing a low percentage of protein. 

In a further series of experiments with bread made from 
different grades of flour from the same type of wheat, it was 
found that the proteins and carbohydrates of bread made from 
straight-run flour show greater " digestibility ' than those of 
bread made from " entire " wheat or Graham (wholemeal) flour, 



See footnote f p. 25. 



f See footnote ° p. 25. 



27 



and the available energy is greater in bread from straight-run 
Hour than in " entire " wheat or Graham bread. (,ki) Actually 82'8 
per cent, of the protein and 91 "5 per cent, of the carbohydrate of 
Graham bread were digestible, whilst for 4i entire " wheat bread 
the values were 86"2 per cent, and 962 per cent., respectively, and 
for bread from straight-run flour 83 "3 per cent, and 97 '7 per cent., 
respectively. Thus, in bread from straight-run flour the protein 
was 6*6 per cent, and the carbohydrate 5'6 per cent, more digestible 
than in Graham (wholemeal) bread. The amount of available 
energy in the bread from straight-run flour was 7*5 per cent, 
more than in the Graham bread. It is stated also that no 
difference was found between the digestibility of bread from patent 
grade flour and straight -run flour. From these data the digestible 
protein and carbohydrates and the available energy were calcu- 
lated for the flours from which the breads were made. The 
results obtained are summarised in Table 16 : — 

Table 16. (67) 

Percentages of Digestible Protein and Carbohydrates, and Avail- 
able Energy in Straight-run, " Entire " Wheat and Graham 
(Wholemeal) Flours. 



Grade of Flour from Hard 


Protein (N X 5-7). 


Carbohydrates. 


Heat of Combustion 
(energy) per gram. 


Spring Wheat. 


Total. 


Digesti- 
ble. 


Total. 


Digesti- 
ble. 


Total. 


Avail- 
able. 


Straight patent (straight- 
run). 
" Entire " wheat 
Graham (wholemeal) ... 


Per 

cent. 
13-60 

13-72 
14-21 


Per 

cent. 
12-01 

11-83 
11-77 


Per 

cent. 
72-04 

70-09 
68-55 


Per 

cent. 
70-31 

67-43 
62-62 


Calories. 
3-861 

3-877 
3-971 


Calories. 
3-510 

3-481 
3-379 



For the definition of terms in this table, see Table 3. 

It will be seen that these results agree with those of the pre- 
vious series given in Table 15. 

In experiments with similar flours from a soft winter wheat 
similar results were obtained ; these are given in Table 17 : — 

Table 17. (&0 

Proportion of Total and Digestible Nutrients and Available 
Energy in Different Grades of Soft Winter Wheat Flour. 



Grade of Flour from 
Soft Winter Wheat 


Protein 
(S X 5-7). 


Carbohydrates. 


Heat of Combustion 
(energy) per gram. 




Total. 


Digesti- 
ble. 


Total. 


Digesti- 
ble. 


Total. 


Available . 


Straight-run flour 
" Entire " wheat flour ... 
Graham (wholemeal) 
flour. 


Per 

cent. 
1092 
1201 
12-24 


Per 

cent. 

10-13 

1029 

9-72 


Per 
cent. 
77-15 
74-17 
7327 


Per 

cent. 
75-61 
6880 
6543 


Calories. 
3-799 
3-860 
3-906 


Calories. 
3-579 
339S 
3226 



28 

Further experiments (69) were carried out with the above three 
classes of flour made from Oregon and Oklahoma wheats, which 
differed greatly from one another in composition; their analyses 
are given in Tables 2 and 5. The results of the experiments are 
summarised in Table 18: — 

Table 18. (i2) 



Grade of Flour. 


Protein 
(N X 6-25). 


Carbohydrates.' 


Heat of Combustion 
(energy) per gram. 




Total. 


Digesti- 
ble. 


Total. 


Digesti- 
ble. 


Total. 


Available. 


Oregon Graham (whole- 
meal) flour. 

Oregon "entire" wheat 
flour. 

Oregon straight grade 
flour. 

Oklahoma Graham 
(wholemeal) flour. 

Oklahoma "entire" wheat 
flour, 

Oklahoma straight grade 
flour. 


Per 

cent. 
8-97 

8-25 

7-55 

16-81 

16-63 

15-06 


Per 

cent. 
5-65 

5-87 

6-41 

12-99 

1324 

13-69 


Per 

cent. 
79-48 

80-35 

81-82 

72-35 

73-05 

73-57 


Per 

cent. 
72-49 

75-61 

80-35 

63-23 

66-11 

71-88 


Calories. 
3-990 

3-900 

3-880 

4-178 

4-159 

4-040 


Calories. 
3-284 

3-420 

3-686 

3-367 

3-485 

3-721 



For a definition of terms in this table, see Table 2. 

It will be seen that the relative nutritive values of the three 
grades of flour from both kinds of wheat, as shown by 
" digestible " protein and available energy, were highest in the 
case of straight grade flour and lowest in the case of wholemeal 
flour, the intermediate position being taken by " entire " wheat 
flour. 

The lower degree of digestibility of the grades of flour con- 
taining bran appears to be dne, at least in part, to the coarseness 
of the particles.* It has been shown that the amount of undigested 
nitrogenous material increased in proportion to the amount of 
outer part of the grain retained in the flour. (37) Furthermore, 
the cell walls of the aleurone layer and of the germ resist the 
disintegrative and digestive action of the juices of the alimentary 
tract. (26) 

But the presence of branny particles even when they are very 
finely divided appears to affect the digestibility of bread. Thus 
the digestibility of bread made from flour to which 14 per 
cent, of very finely divided bran was added has been com- 
pared with that of bread made from flour without bran. The 
results of the experiment are given in Table 19 : — 



* "Various attempts have been made commercially to utilise more fully any 
nutritive qualities which bran may possess. Many of these consist in grinding 
the branny particles to an extreme degree of fineness. In one case the bran is 
made into a paste with a one per cent, solution of common salt containing a little 
lime ; the paste is dried and ground to a fine powder which may then be mixed 
with ordinary flour. It is claimed that the powder tbus obtained from bran is 
as digestible as ordinary white flour. (9) 



29 
Table 19. (73) 



Kind of Flour. 


Protein 
(X X 0-25). 


Carbohydrates. 


Heat of Combustion 
(energy) per gram. 




Total. 


Digesti- 
ble. 


Total. 


Digesti- 
ble. 


Total. 


Available. 


Straight grade flour with 
bran added. 

Straight grade flour with- 
out bran. 


Per 

cent. 
15-35 

15-06 


Per 

cent. 
13-19 

13-69 


Per 
cent. 
72-23 

73-57 


Per 

cent. 
67-46 

71-88 


Calories. 
3-876 

4-040 


Calories. 
3-395 

3721 



For a definition of terms in this table, see Table 2. 

It will be noticed that there was a somewhat larger percentage of 
total proteins and a smaller percentage of carbohydrates in the Hour 
containing bran than in that without bran, but, nevertheless, 
the available energy and the digestibility of the protein and 
carbohydrate were slightly less in the Hour containing bran than in 
the flour free from bran. 

In Table 20 the " digestibility " of Graham flour, " entire " 
wheat flour, and straight-run flour, is compared with the digesti- 
bility of flour to which as much bran was added as was removed in 
the milling. The bran before being added was very finely 
ground : — 



Table 20. 



(73) 



Protein and Carbohydrate Digested from Different Kinds of 
Flour from the same Wheat. 



Kind of Flour. 



Graham (wholemeal) flour ... 
" Entire" wheat flour 
Straight grade flour with bran added 
Straight grade flour ... 



Protein. 



Carbohy- 
drates. 



Per cent. 
77-3 
79-6 
85-9 
90-9 



Per cent. 
87-4 
90-5 
93-4 
97-7 



For a definition of terms in this table, see Table 2. 

It would appear from these results that the finer grinding of 
the bran increases its digestibility to some extent; but, apparently, 
the defective digestibility of bran is not entirely due to imperfect 
grinding, because flour containing bran, even when the latter 
is very finely ground, is still less digestible than flour free from 
bran ; this would seem to indicate that bran has some inherent 
property of resisting the digestive juices. (:4) 

In this connection the results obtained in some English experi- 
ments are of interest; it has been found that when milk is taken 
with wholemeal bread 3 per cent, less milk was digested than 
when the milk was taken alone. (13) 



30 

It has been shown that bread made from rye flour free from 
bran is better digested than bread made from rye flour containing 
bran, even though the latter has been very finely ground. (34) 
Other investigations on this point have confirmed the above 
results, and have led to the conclusion that the digestibility of 
bread made from rye flour is impaired unless at least 15 per cent, 
of the branny portion of the grain is removed. f32) 

On review of the whole series of experiments above referred 
to, perhaps the most important consideration, so far as relates 
to available or " digestible ' protein and energy, is that the 
differences in nutritive value between various grades of flour made 
from the same wheat are usually insignificant when compared with 
the differences in nutritive value of flours made from wheats 
differing widely from one another in composition. 

Fat. — The question of the fat-content of flours may here 
be considered. Though the variations in the fat-content of dif- 
ferent grades of flour may be relatively considerable, they are 
absolutely small. Removal of the germ diminishes the fat- 
content, but the diminution is hardly appreciable. Even in flour 
which is rich in fat the amount present is so small as to be of 
little value dietetically. The variations which occur in different 
grades of flour are of correspondingly little account from the 
dietetic point of view. 

The Germ.. — As already mentioned, the addition of germ to 
white flour in the proportion in which it has been removed in 
milling can increase the protein content of the flour by less than 
one per cent. If the germ which can actually be extracted and 
recovered were added to the flour, the increase would be at most 
half of the above small increase. This extra protein is prac- 
tically as digestible as the protein of straight-run flour itself, 
and on reference to Table 2 it will be seen that its caloric value 
is approximately the same as that of flour ; further, the available 
energy in flour containing 7 per cent, of added germ was not 
greater than the available energy of flour free from germ. (75) 
The germ is richer in phosphorus-containing compounds (e.g., 
nuclein) than the rest of the grain, but the absolute amount of 
these substances which the germ contributes to the flour is 
minute. It should be remembered that the variations in protein 
content of flour dependent upon the variety of wheat from which 
it has been milled are very much greater than those resulting 
from the inclusion or exclusion of the germ. The fact that the 
germ is the portion of the grain in which the vital processes are 
most active, has led to the idea that its removal deprives flour 
of valuable vital qualities, and this view has found expression in 
a belief in the value, from a nutritive standpoint, of the enzymes 
contained in the germ. These enzymes, however, are destroyed 
by heat in the baking of bread. Apart from general dietetic 
considerations, there appears to be some evidence that the germ 
may contain substances of special dietetic value in cases where 
the diet is mainly, if not entirely, restricted to bread. Further 
attention is directed to this aspect of the question in a later 



31 



section of this report (see p. 35 et seq.). As said above, the 
protein of the germ is of a different nature from that contained in 
flour from the endosperm. 



Mineral Requirements. 

The mineral matter in an ordinary mixed diet amounts to 
about 20 grams daily, and is obviously more than sufficient 
for all the needs of the body. Since mineral substances are 
absorbed and also excreted by the intestine, it is impossible by 
a mere comparison of intake and output to ascertain how 
much has really been absorbed, quite apart from the more im- 
portant question as to how much has undergone assimilation. 
Although practically no data are forthcoming as to the total 
mineral requirements of the body, indications have been obtained 
as to the amounts of certain elements such as phosphorus, calcium 
and iron, which may be needed. It has been possible in the 
case of certain inorganic elements to ascertain the equilibrium 
point at which their intake in the food is equal to their output 
in the excretions while the amount of the elements in question 
in the body remains constant. It does not, however, follow that 
such equilibrium indicates the minimum upon which the body 
can subsist, nor conversely does it follow that the attainment of 
equilibrium necessarily implies an adequate supply of the 
elements in question. Thus it has been found possible to main- 
tain phosphorus equilibrium in young animals with about one- 
fifth of the amount taken by normally fed control animals, 
although judging from the symptoms which eventually develop, 
the former animals were clearly receiving an insufficient 
supply/ 245 

An adequate supply of mineral substance is provided for the 
infant in the mother's milk ; it is possible, therefore, to ascertain 
from the composition of the milk the amount of mineral sub- 
stance which will satisfy the requirements of the child. When 
six months old the child consumes about 1 litre of milk daily 
containing about 25 grams of salts, which in round numbers 
include 0*5 gram of calcium and about the same amount of 
phosphoric acid (P o 5 ). fl) An infant two months old has 
been found to assimilate 0*15 gram of mineral matter " and 
a five months old child 045 gram of mineral matter daily. (5) 
It has been shown that an infant in the early months of life 
receiving a daily supply of milk containing 1*4 grams of mineral 
matter assimilated 50 per cent, of this, which apparently included 
practically the whole of the lime and phosphoric acid present 
in the original milk. (6) Growth is most active during the first 
year of life, and after this period it is probable that the mineral 
requirements of the body become relatively less, though the 
body weight increases. 

Investigations into the phosphorus requirements of the body 
have led to the conclusion that from 1 to 2 grams of phosphorus 
is sufficient for the daily needs of an adult. (8)(41) Becent American 



32 

experiments would appear to indicate that 0*9 to 1*5 grams of 
phosphorus would meet the daily requirements/ 773 

The large variations in the requirements of phosphorus 
would seem to be accounted for in part, at any rate, by the 
different digestibility of different phosphorus-containing com- 
pounds ; it would seem that phosphorus is more valuable for 
nutrition in certain combinations than in others. Thus^ it has 
been found possible to maintain phosphorus equilibrium with 
less phosphorus when this is taken in the form of casein than 
when taken in the form in which it occurs in meat. (14) 

The requirements of the adult body for calcium have been 
variously given at 0"6 gram of calcium (21) (0*84 gram of lime), 
0*68 to 0*86 gram of calcium (33) (0*95 to 1*2 grams of lime), 
07 gram of lime (77) , 1*5 grams of lime C28) , and by Bunge at 
33 grams of lime daily. Albu and Neuberg consider that any 
diet supplying less than 1 to 1*5 grams of lime daily is poor in 
calcium. (2) 

As regards iron, the requirements of the body appear to be 
met by about 10 milligrams of this element daily. (76) 

The above quantities must be taken as indicating only the order 
of magnitude of the requirements of the body in respect of the 
elements mentioned; much more work requires to be done on the 
subject of the mineral needs of the body before definite pro- 
nouncement on this subject can be made. 

In an investigation into the metabolism of calcium, mag- 
nesium, and phosphorus conducted by the United States 
Department of Agriculture, it was found that in a large number 
of typical daily dietaries the amount of phosphorus fell below 
1*5 grams per day. (77) This raises a doubt as to whether these 
dietaries supplied an adequate amount of phosphorus for the needs 
of the body. So much, however, depends upon factors such as 
the availability of the phosphorus for nutrition and upon other 
considerations, the knowledge of which is at present very 
incomplete, that judgment on this point must be suspended. 

To what extent a diet exclusively composed of bread made 
from different kinds of flour is able to satisfy the bodily require- 
ments of an adult in regard to mineral matter may now be 
considered. On reference to Tables 5, 6, and 7 it will be observed 
that the ash contents of different kinds of bread vary considerably 
amongst themselves. From these analyses it will be seen that 
Graham (wholemeal) bread contains from 0*95 per cent, to 1'54 per 
cent, of ash, bread from " entire " wheat flour contains from 
0*52 per cent, to 0*94 per cent., bread from straight-run flour 
contains from 0*3 per cent, to ()"9 per cent., whilst bread from 
patent grade flour may contain as little as 0'27 per cent, of ash. 

ISTo information is forthcoming as to the composition of these 
ashes, but it may fairly be assumed that they approximate in 
composition to the ashes of the flours from which the corre- 
sponding bread was made. Taking into account these and other 
analyses of bread, it may be assumed for present purposes that 



33 

the average mineral content of white bread made from ordinary 
straight-run flour will amount to about 0'6 per cent., apart from 
added salt. Similarly, Graham bread may be taken as con- 
taining on an average about 1'3 per cent, of ash. 

Two-and-a-half pounds of white bread made from an ordinary 
straight-run flour, a quantity which, in the absence of other 
food, will suffice for the average daily needs of an adult when 
judged by energy value (see p. 24), will contain nearly 
7 grams of mineral matter. A similar amount of Graham 
(wholemeal) bread will contain about 14 grams of mineral matter. 
On the assumption that the ash of bread corresponds in com- 
position to that of flour from which it is made, the amount of 
phosphorus in two-and-a-half pounds of white bread will be about 
I'D grams ; whilst the same amount of wholemeal bread will 
contain about 3 grams of phosphorus. On the assumption that 
5 per cent, of the ash consists of lime, the above amount of 
white bread will contain about 0*35 gram of lime. Since the 
ash of wheat contains about 3 per cent, of lime, the amount of 
lime in 2\ lbs. of wholemeal bread will not on the above data 
exceed 05 gram. 

Ordinary white bread contains about O'OOl per cent, of iron, 
which means a daily supply of rather more than 11 milligrams of 
iron in 2 \ lbs. of bread. Graham (wholemeal) bread may contain 
twice or three times the amount present in white bread. 

Assuming that the elements are absorbed in the proportion in 
which they exist in the ash, it would appear from the foregoing 
data, apart from any consideration of loss due to imperfect 
absorption, that the requirements of the body are approximately 
met, as far as phosphorus and iron are concerned, by ordinary 
white bread when taken in amounts which may roughly be 
considered sufficient for daily needs of nitrogen and energy. 
Wholemeal bread would, however, furnish a more generous 
supply of both phosphorus and iron. Bread made from " entire " 
wheat flour would in this respect occupy a position intermediate 
between wholemeal bread and ordinary white bread. Both white 
bread and wholemeal bread are deficient in calcium, and if bread 
alone is relied on for food purposes, an insufficient supply of this 
element will be afforded especially when growth is still going 
on. It has been shown in the case of animals that, even when 
the phosphorus in food is adequate, deficiency in calcium leads 
to abnormalities in skeletal growth (osteoporosis).^ It would 
seem to be important, therefore, that during the period of skeletal 
growth the CaO : P 2 5 ratio should be sufficiently high. In 
wheat and all forms of flour derived from it the above ratio 
is low. 

The above conclusions as to the sufficiency of the mineral 
supply are based on the assumption that the absorption of 
mineral matter from the breads in question is complete. But 
investigations as to the amount of mineral matter absorbed by 
the body from different kinds of bread are few and unsatisfactory. 
They resolve themselves mainly into an estimation of total 
mineral matter in the bread eaten and in the faeces, the difference 
being taken as representing the amount of mineral matter 

20420 C 



34 

absorbed. In many cases the added salt in the bread is not taken 
into consideration, and in one case (38) where attention has been 
paid to the salt (sodium chloride) content of the bread erroneous 
conclusions have been drawn from the published accounts of the 
experiments, which have been quoted as evidence that more 
mineral matter is absorbed from wholemeal bread than from 
white bread. Certain experiments seem to show that about 50 
per cent, of the ash of wholemeal bread may be lost in the fasces. (81) 
Other experiments confirm this and also indicate that from white 
bread about 27 per cent, of the mineral matter is lost. (13) If this 
be correct equal amounts of wholemeal and white bread should 
yield about the same amount of mineral matter to the body, and 
the mineral content of white and wholemeal bread cannot be 
taken as representing the amount of mineral matter available for 
the body in these varieties of bread respectively. Finely grind- 
ing wholemeal facilitates the absorption of the mineral matter it 
contains, but even then it is probable that the absorption is not so 
complete as in the case of white bread, although the absolute 
amount of mineral matter available for the body is greater. 

Information regarding the absorption of the different com- 
ponents of the mineral matter of bread is lacking. Thus although 
wholemeal bread contains more iron than white bread there is 
no evidence to show whether the iron is equally available in the 
two varieties of bread. 

The combinations in which phosphorus occurs in food would 
appear largely to influence its availability for the needs of the 
body. As already mentioned, there are indications that the phos- 
phorus in casein is of greater nutritive value than that of meat, 
and that phosphorus in phospho-proteins is more valuable from a 
nutritional standpoint than inorganically combined phosphorus. 

Differences of opinion still exist as to whether the body can 
utilise phosphorus from inorganic sources. Recent woik on this 
subject would seem to indicate that when there is a deficiency 
in the supply of organically combined phosphorus the body is 
capable of making good the deficiency, to some extent at any rate, 
from inorganically combined phosphorus. (17) (21) Schaurnann (40) 
is of opinion that although inorganic phosphorus compounds may 
be able to maintain phosphorus equilibrium, they cannot replace 
those organic phosphorus compounds of the food which appear to 
have specific functions in the nutrition of the body. 

It would appear that the phosphorus in bran is present in great 
part, if not entirely, in organic combination, probably as phytin 
(see p. 21), and can be extracted by means of dilute acid. (30) It 
has been shown that when phytin is administered to man, only a 
small portion is retained by the body, the remainder appearing 
in the faeces as inorganic phosphate. m Further experimental 
investigation is, however, required to ascertain how far the 
phosphorus of bran is available for nutrition. 

From certain experiments recently carried out at the 
University of Cambridge it appears that young rats fed on 
a diet consisting exclusively of white bread did not thrive 
so well as those fed upon a diet consisting of wholemeal 
bread only. Although these experiments were of a preliminary 



35 

character only, the results obtained are sufficiently remarkable 
to warrant further investigation. Young' rats, weighing- about 
30 grams, fed upon wholemeal bread increased in weight by about 
75 per cent, in three weeks, whereas, similar young rats fed 
for the same period on white bread showed an increase in weight 
of about 15 per cent. only. Acetic acid extracts of the whole 
meal bread added to the white bread caused a decided improve- 
ment in the condition of the rats fed on white bread, but the 
results thus obtained were inferior to those obtained by feeding 
rats on wholemeal bread itself. Experiments along- similar lines 
are proceeding at the University of Liverpool, and a preliminary 
note of the results already obtained has been published. (7) 
The animals used were pigeons which were fed on white bread and 
on bread made from flour containing different amounts of offal 
(wholemeal and so-called " standard " flour respectively). The 
birds fed on wholemeal and so-called " standard " bread remained 
normal, whereas those fed only on white bread lost weight and 
suffered from peripheral neuritis. The addition of yeast to the diet 
was sufficient to restore them to a healthy condition. 

Leonard Hill (l9) has carried out a number of experiments in 
which certain rats were fed on white flour and others on so-called 
1 standard flour," which is equivalent to ordinary flour containing 
a somewhat variable proportion of finely ground offal. He states 
that the rats fed on the " standard " flour throve much better 
than those fed on white flour; this defect in the nutritive quality 
of white flour could be removed by the addition of a small per- 
centage of germ. He attributes the value of germ in this con- 
nection to the presence therein of certain amino-groupings 
essential for growth and readily available for nutrition. 

At the present stage of these investigations it is impossible to 
say with certainty to what factors the differences in nutrition 
observed are due. It is known that the absence of relatively 
indigestible fibrous material in the diet of animals, such as rats, 
is prejudicial to their health ; and this may, in part at any rate, 
account for the results mentioned above. The differences observed 
may also be attributed to the paucity of mineral matter, possibly 
phosphorus, in white flour. The fact that the greater part, if 
not all, of the phosphorus in the bran c-m be extracted by means 
of dilute acids, suggests that the improvement in the condition 
of the rats fed upon white bread to which an acetic acid extract 
of wholemeal had been added may have been due to an increased 
supply of phosphorus. Should a defective supply of mineral 
matter prove to be the reason for the differences observed, it 
should be remembered that animals which rapidly reach maturity 
require a relatively greater supply of mineral matter than 
animals which develop slowly, and a food that contains in- 
sufficient mineral matter for one class of animals may furnish 
an adequate supply for another class. The investigators who 
have conducted these experiments are inclined to ascribe the 
differences observed not to mineral matter but to some unknown 
substance residing in the branny coats of the grain. 

In this connection reference may be made to work which has 
been done on the aetiology of beri-beri. It would appear that a 

20420 C 2 



36 

diet consisting exclusively of rice from which the skin or cuticle* 
has been removed may give rise to a disease commonly known as 
beri-beri, which manifests itself by polyneuritis and other symp- 
toms. It has been shown that polyneuritis, analogous to that 
which occurs in beri-beri, can be produced in animals by feeding 
them on rice which has been deprived of its cuticle by milling. If 
the offal which has been removed from rice, and which amounts to 
about 10 per cent, of the grain, be returned to the rice, no poly- 
neuritis occurs. 

Schaumann (10) has reviewed in an exhaustive manner the work 
which has been done on this subject. He concludes that beri-beri 
is a disease of disordered metabolism resulting from an insufficient 
supply of organically combined phosphorus in the diet, and in 
some few cases to inability on the part of the body to utilise the 
phosphorus of the food. Polyneuritis, simulating in many re- 
spects the symptoms of beri-beri, can be produced experimentally 
in animals by feeding them on a diet poor in organically com- 
bined phosphorus. The addition to such a diet of protein, of 
various inorganic salts (including phosphates), and of artificially 
prepared organic phosphorus compounds, such as glycerophos- 
phates, is without avail in preventing the onset of symptoms or in 
removing them when they have appeared. The addition, how- 
ever, even in small amounts, of certain substances rich in organic 
phosphorus, e.g., yeast, bran and peas, prevents the onset of 
disease or cures it when established. Such organic phosphorus- 
containing substances as phytin from bran and nucleic acid from 
yeast protect to only a limited extent from the onset of the disease, 
and exert only a transient curative action. The addition of inor- 
ganic phosphorus compounds to the diet does not cure the disease 
nor prevent its onset. Schaumann is of opinion that although 
inorganic phosphorus compounds may be able to maintain phos- 
phorus equilibrium they cannot replace those organic phosphorus 
compounds of the food which appear to have specific functions in 
the nutrition of the body. He accounts for the superiority of bran 
over phytin and of yeast over nucleic acid on the supposition that 
bran and yeast contain other organic phosphorus compounds as 
yet unknown, which are essential for the normal nutrition of the 
body. 

As a result of further work, (10) it would appear that the sub- 
stances which prevent the occurrence of the disease can be ex- 
tracted from rice offal by means of dilute hydrochloric acid (0'3 
per cent.), and are not precipitated from the solution by alcohol 
(proof spirit strength). The phytin which is extracted by acid 
from the offal is precipitated by this means. 85 per cent, of the 
phosphorus of the offal including that of the phytin has been 
sli own to be ineffective in preventing the onset of polyneuritis. 

* In the milling of rice for sale in this country the cuticle consisting of 
pericarp, testa and nucellus is removed together with the germ and a varying 
amount of the aleurone layer {see my report to the Local Government Board 
on " ' Facing ' and other methods of preparing rice for sale." Reports of 
Inspectors of Foods, No. 8, 1909). Jn this country where rice enters into the 
ordinary diet to only a small extent the removal of the cuticle is unimportant 
from a health point of view. 



37 

The substances soluble in alcohol (proof spirit strength) do not 
exceed 1*6 per cent, of the grain, and when added to rice deprived 
of its cuticle are efficacious in preventing the onset of disease. 
The nature of the active substance is not known. 

It would seem as if the disturbances of normal metabolism re- 
sulting in the production of characteristic symptoms are due to an 
insufficient supply in the food not simply of certain elements such 
as phosphorus, but of particular combinations or groupings of 
elements which seem to be necessary for the normal nutrition of 
the body. Phosphorus may, of course, be an essential constituent 
of these hypothetical combinations or groups. 

If results analogous to those just described were to be obtained 
in the case of bread, and the application of these results to man 
could be justified, a strong argument would be afforded for the 
inclusion of the offal in flour in cases where bread forms practically 
the whole of the diet. 

In the present imperfect state of knowledge as to the mineral 
requirements of the body and the manner in which these may be 
met, it may be well to substitute very finely ground "entire" 
wheat bread for a portion at any rate of the white bread in the 
diet in cases where an ample supply of mineral matter appears 
necessary, such for example as growing children or during preg- 
nancy or where other food is not obtainable. In this way a 
somewhat larger supply of mineral substances may be ensured 
than would be obtained from fine white bread alone. 

Individual Preference : Need for Variety in Diet. 

The work of Pawlow and others has demonstrated the importance 
of the aesthetic or psychic element in the digestion of food, and it 
seems established that food which is pleasant and palatable is 
digested more readily than if it were consumed in a less interesting 
form. Due regard therefore should be paid to individual taste in 
introducing, for example, a wholemeal bread into a dietary to 
replace a white bread lest otherwise attempts at improving the 
diet may be rendered nugatory. From the same point of view an 
agreeable or characteristic flavour in bread, such as the " nutty ' 
flavour imparted by the germ, may have distinct dietetic value. 

In considering the question of the comparative nutritive values 
of white and wholemeal bread, it has been necessary to assume 
that the diet consists wholly of the one or the other. In practice 
this is rarely the case, although it is to be feared that too fre- 
quently bread figures more exclusively in the diet of many children 
than it should. Monotony in diet is to be avoided; all protein 
is not the same protein, and the body may require, for health, 
groupings of elements which may be present in one variety of 
foodstuff but absent in another. Definite experimental evidence 
exists in support of this Y i e w, (L,0)(40)(78K79) and the physiological 
utility of introducing variety into diet is being more generally 
realised. A diet consisting wholly of bread is very undesirable 
from many points of view, and even assuming that the above 
surmises as to the dietetic value of offal should prove correct, the 



38 

presence of offal in bread would only diminish and not abolish the 
objections to diet of this monotonous character. If bread were 
supplemented with other foods, such as are ordinarily present in 
an average liberal mixed diet, the advantages which one variety of 
bread may possess over another become for dietetic purposes 
practically negligible. 

The Undigested Residue of Bread. — This residue is greater in 
wholemeal bread than in bread made from highly refined flour. 
Wholemeal bread is said to possess laxative properties owing to 
the irritating effect of the branny particles on the intestinal walls, 
and on this account has been assumed to be useful for those en- 
gaged in sedentary occupations. This laxative effect, however, 
is said to disappear if such bread is constantly used. Whether 
wholemeal bread really possesses laxative properties is open to 
question ; certain experimental results would appear to show that 
on a diet of coarse bread the fasces were more slowly excreted than 
when fine bread was consumed. (38) In a certain number of the 
American feeding experiments referred to in this report, symptoms 
of gastro-intestinal irritation manifested themselves as a result of 
the ingestion of bread containing branny particles. 

The Effect of Bread on the Teeth. 

It is asserted that the use of white bread is responsible for 
much of the defective teeth of the present day. Defects occur- 
ring in the teeth of children whose main diet is white bread have 
been attributed to imperfect formation of the teeth owing to the 
relative poverty of white bread in the mineral constituents neces- 
sary for the growth of the teeth. 

Improper feeding during the earlier months of life may, and 
probably does, exert a prejudicial influence upon the development 
of the teeth. It should be remembered in this connection that 
many of the teeth which become carious in children are developed 
before bread should form any part of the diet. 

Apart from any developmental considerations, however, there is 
evidence that food rich in carbohydrates may exert a locally 
harmful effect on teeth. If particles of starchy material such as 
bread are allowed to accumulate on or between the teeth, acid is 
produced from the carbohydrates of the bread through the agency 
of acid-forming bacteria, and this acid gradually erodes the teeth. 
The enamel in contact with the decomposing food is first 
decalcified, and in this way a breach is formed through which in* 
vading organisms may pass and attack the less resisting dentine. 
It is therefore desirable to prevent the accumulation of carbo- 
hydrate around the teeth. Some dental authorities insist that 
white bread, owing to its softness, adheres more readily to the 
teeth than wholemeal bread which contains fibrous branny 
particles, and that the greater amount of mastication which the 
latter bread requires prevents the accumulation of particles of food 
around the teeth and the subsequent formation of acid and conse- 
quent destruction of the teeth. This may be so, but whether the 
use of wholemeal bread materially prevents the accumulation on 
the teeth of the very small amount of carbohydrate material said 



39 

to be a factor iii the inception of caries is not yet conclusively 
proved. Any advantages of a detergent nature which wholemeal 
bread may possess would be less marked in bread made from flour 
containing only a portion of the bran of the wheat, such as 
" entire " wheat flour, including " standard " flour. It is com- 
monly stated that the acid-forming micro-organisms of the mouth 
produce acid more readily and in greater amount from ordinary 
white bread than from wholemeal bread, and this excessive forma- 
tion of acid is said to have a prejudicial action on the teeth. 
Whether such differences in acid production really exist cannot 
be said to have been satisfactorily established. Determinations 
of the amount of acid produced when so-called standard bread 
and ordinary white bread are chewed in the mouth have recently 
been made ; only slight differences could be observed in the 
amount of acid produced in the two cases. (20) 

It is known that the enamel of teeth contains a small amount 
of calcium fluoride. Gabriel (11) concludes that the ash of teeth does 
not contain more than 0*1 per cent, of fluorine, and .Jodlbauer ( " 3) 
obtained slightly higher values. Harms fl5) considers that 
Gabriel's estimate is much too high, and states that the ash of 
human teeth contains only about 0'006 per cent, of fluorine. 

It has been stated that carious teeth are poorer in fluorine than 
normal teeth ; Hempel and Scheifler (l8) came to the conclusion, as a 
result of one or two isolated analyses, that healthy teeth were richer 
in fluorine than carious teeth. Michel (25) could find no difference 
between the fluorine content of healthy and carious teeth, and 
Wrampelmeyer (82) was unable to discover any relationship between 
the fluorine content and the healthiness of teeth. Results such as 
these are inconclusive since the fluorine content of a carious tooth 
would vary according to the part of the tooth which was destroyed 
by the disease. Bertz (3) has found that more than twice as much 
fluorine is present in the enamel as in the dentine of teeth ; if the 
enamel is destroyed by caries to a greater extent than the dentine 
the percentage of fluorine in the tooth as a whole will be 
diminished. 

It has been suggested that bread made from ordinary white flour 
is deficient in fluorine, and on this account if such bread be con- 
sumed the formation of enamel may be defective and may pre- 
dispose the teeth to decay. No evidence can be adduced in support 
of this contention. Practically nothing is known as to the fluorinb 
content of wheat and flour, although it has been ascertained that 
fluorine in minute amounts is widely distributed throughout the 
vegetable kingdom. " Flour probably contains a trace of 
fluorine, though possibly less than is present in bran. A mere 
trace of this element, however, in any flour would probably be 
sufficient for the formation of enamel were it necessary for the 
organism to rely for this purpose on bread for its supply of fluorine. 
But the enamel of teeth which are prone to decay in later life is 
formed before bread enters into the dietary. The minute trace of 
fluorine present in the maternal blood (42)(88) and in milk (in the 
latter amounting to 0*00003 per cent.) (42) is sufficient for the needs 
of the child during this period of rapid growth and tooth formation. 



40 



III.— SO-CALLED " STANDARD " FLOUR AND BREAD. 

Although tlie use of white bread lias long been almost universal 
in this country, there have always been those who have taken 
objection to the habitual use of flour from which the maximum 
quantity of " offal " has been removed, especially since the 
introduction of roller-milling. The views of many of these 
objectors has probably been mainly determined by personal pre- 
ference ; they have found, for example, that bread containing a 
material proportion of bran and other millers' " offal' is for 
them more satisfying or relieves them of digestive troubles, or 
they have been attracted by the pleasant flavour and distinctive 
appearance of bread which has been made from stone-milled 
flour, or of certain types of brown bread, and being thus habitu- 
ated look with considerable suspicion upon the extremely white, 
and frequently " overproved " and tasteless loaves in general use. 
When consideration is given to some of the practices which have 
come to be adopted by millers with the object of producing the 
whitest looking bread, or of making the " boldest " looking loaf 
from the smallest quantity of flour, this suspicion cannot be said 
to be without warrant.* 

Others have based their objections on wider grounds; upon the 
alleged inferiority of ordinary white bread in protein, and its 
deficiency in mineral matter ; upon the advantages of the retention 
of the outer coat of the wheat grain on account of its richness in 
mineral matter and as an aid to the preservation of the teeth, and of 
the germ on account of its being of itself of high food value and 
containing food material which is not present in the endosperm. 
These contentions have lately been put forward prominently by 
the Bread and Food Reform League, which has in these matters 
collected opinions from medical, dental, and other authorities who 
are in accord with the general object of the League. In the fore- 
going pages I have discussed the principal experimental evidence 
which, as far as I have been able to find, bears upon these con- 
tentions. Some of these contentions, I think, have been based on 
erroneous inferences, while others must be regarded as speculative, 
rather than as resting on well-established observations. The recent 
activities of " bread reformers " have, nevertheless, been of dis- 
tinct utility in familiarising the public with the fact that whole- 
some and palatable bread can be supplied which contains a 
material proportion of millers' " offal " in addition to the 
endosperm flour, that the presence of this " offal " is by no means 
necessarily objectionable, and may to some individuals be advan- 
tageous, and that mere whiteness and excessive " boldness " of a 
loaf are very artificial standards of quality. 

Until recently, those who did not wish for white bread from 
patent or " households " flour, frequently could obtain as an 
alternative from the baker only one or other form of wholemeal 
loaf — an article which was sometimes unpalatable or liable to be 
irritating in its effects on account of the bran being in excess, or 
in too coarse a state. The output of stone-milled flour, 



See footnote f , p. 1. 



41 

was too limited to be in anything like universal use by 
bakers, and the same might be said for special flours sold under 
fancy names such as the germ flours referred to on p. 9. An 
attempt has lately been made to secure the general adoption for 
bread making of a flour which retains a considerable portion of the 
millers' offal, including germ — under the name of " standard ' 
or " 80 per cent." flour — which can be produced not only by the 
stone-mill, but in any roller-mill by omitting or modifying certain 
of the later stages of refining. Bread made from this flour has 
lately been brought so prominently before the public that it seems 
necessary, for the purposes of this report, to give some account 
of it. 

Preparation and Composition of so-called 
" Standard " Flour. 

In wholemeal prepared from an average wheat the coarse branny 
particles amount to about 20 per cent, of the whole grain. A 
flour from which this bran has been removed, therefore, amounts 
to 80 per cent, of the grain ; it contains the whole of the contents 
of the endosperm cells (with the exception of a small amount left 
adhering to the coarse bran in the form of floury particles), the 
germ, and a certain amount of finely comminuted branny particles 
and cell walls of the endosperm. 

Flour of this kind has been described as consisting of " 80 per 
cent, of the grain with all the germ and semolina." As an 
alternative it has been suggested that this flour should be described 
as consisting of that 80 per cent, of the grain which contains the 
least amount of fibrous particles (cellulose, bran, &c). It is 
commonly known as " 80 per cent." or " standard " flour, and the 
same terms are applied to bread made from the flour. 

So-called " standard " flour can be prepared either by stone- or 
roller-milling processes. If milled by stones, the wholemeal 
resulting from the grinding operations is subjected to sieving, 
whereby coarser branny particles to the extent of about 20 per 
cent, of the wheat are removed, the resulting flour amounting to 
about 80 per cent, of the wheat milled. 

When " standard" flour is prepared by roller-milling, it is 
usual, in order to avoid extensive alterations in the disposition of 
the milling machinery, to subject the wheat to practically the 
same series of processes as in the preparation of an ordinary 70 
per cent, straight-run flour. In order, however, to obtain an 
80 per cent, flour, slight modifications which differ in detail in 
different mills are made in the mode of dealing with the offal. 
Broadly speaking, it may be said that the offal formed in the 
break roller system is removed as such. This amounts on an 
average to somewhat under 20 per cent, of the whole grain and 
consists of bran and pollard. The offal (sharps or middlings) 
which is ordinarily removed during the process of reduction is 
returned to the flour, with the exception of the larger branny 
particles (about 2 per cent, or 3 per cent, of the grain) which are 
rejected. The resulting product is an 80 per cent, flour containing 
the more finely ground portions of offal, e.g., fine branny particles, 
fibre, and the germ in a flattened and broken condition. The offal 
with the germ is commonly passed through closely corrugated 



42 

rollers known as " scratch rollers " in order to break it up as 
finely as possible before allowing it to pass into the flour. In 
some cases, millers extract as much of the germ as they can, 
grind it separately to a fine powder and then add it to the flour. 
The germ may also be cooked before being ground. 

Flour prepared in this way may be considered as an 80 per cent. 
" straight-run " (see p. 12) including the germ, or as a 70 per 
cent. " straight-run " with the addition of 10 per cent, of the 
more finely divided offal, including the germ. 

It is, however, possible to make other mixtures of flour and offal 
which will simulate very closely 80 per cent, flour made in the 
above way. Thus the requisite amount of finely divided offal may 
be added to " households " or other commercially low grade 
flour, and the product so obtained would be cheaper to manu- 
facture than an 80 per cent straight-run flour. For example, in 
ordinary milling 40 per cent, of the flour may be removed as 
" patents," leaving 30 per cent, of commercially lower grade or 
" household " flour. If TO parts of the latter are taken and 10 
parts of fine offal be added to it, a flour is produced which will 
closely simulate an 80 per cent, straight-run. Or again, 60 parts 
of a commercially low grade flour and 20 parts of fine offal from a 
white wheat could be mixed; or the offal used may be of any 
commercial quality, purchased for the purpose of adding to flour 
of the " household " type. Such flour can be made at a cost of 
from 25. 6d. to 35. per sack less than an 80 per cent, straight-run ; 
the pecuniary gain which the miller can effect in this way is 
considerable. Much so-called " standard " flour is prepared in 
ways such as these. 

Those who have introduced and endeavoured to popularise 
" standard flour " regard it as properly an " 80 per cent, 
straight-run " containing germ, and object to preparations of the 
above kind on the ground that they do not contain the whole of the 
flour of the wheat, a portion having been removed as patent grade 
flour. For convenience, the term " imitation standard " may be 
applied to the latter preparations. 

The ordinary tests as to appearance and colour as applied by 
millers may serve, in the hands of those accustomed to examining 
milling products, to detect the difference between a genuine 
" standard " and an " imitation standard " flour from the same 
wheat. When, however, the flours are prepared from different 
kinds of wheat the tests are not so reliable. It is possible to 
prepare an " imitation standard " flour from white wheat with 
white offal, which will have a better colour, from the millers' 
point of view, than a genuine " standard " flour prepared from a 
wheat in which the offal is darker in colour. Moreover, the 
difference in colour between loaves made from genuine and imita- 
tion " standard " flours may be less marked than the difference in 
colour between the flours themselves. 

It is not an easy matter to mill flour which is exactly 80 per 
cent, of the wheat, and much of the so-called " 80 per cent." or 
" standard " flour now sold may actually represent rather more 
and in some cases less than 80 per cent, of the wheat milled. 

The flavour of "80 per cent." or " standard " flour made from 
white wheats is said to be superior to that of similar flour made 



43 

from red wheats, partly oil account of the harshness which offal 
from the latter variety of wheats imparts to flour. It is stated 
that the flavour of bread made from a carefully prepared genuine 
i( standard " (80 per cent.) flour is superior to that of bread made 
from " imitation standard " flour. 

This opinion, together with the greater cost of production of 
" standard " flour, which can be said to include all the material 
which in roller-milling would be represented by " patent " flour, 
is in a large measure responsible for the demand which has arisen 
in some quarters for the prescription of an official definition of 
" standard " flour in terms of its composition, which should 
exclude what I have termed " imitation standard " flour and 
ensure the provision of an article of definite and known manu- 
facture and composition. It is not, however, at present clear that 
any definition which has so far been proposed would be of practical 
value for the purpose. 

The definition in which so-called " standard " flour is described 
as " 80 per cent, of the wheat with all the germ and semolina," ie 
unsatisfactory for more than one reason. In the first place the term 
semolina does not connote any particular part of the grain ; it is 
merely a trade name for the coarser fragments of endosperm pro- 
duced in the break-roller system, and is, therefore, incapable of 
exact definition. In the second place the requirement that the flour 
shall contain 80 per cent, of the wheat. grain is by no means satis- 
factory as a " standard " of quality or composition. Wheats differ 
considerably from one another, and the skin or branny envelope 
bears a smaller ratio to the endosperm in the case of a large grain 
than of a small grain. Thus, in certain small-grained wheats, 
such as some Russian wheat, the proportion of the skin to endo- 
sperm is large, and it is not possible to obtain more than 60 per 
cent, of such grain as ordinary flour. Obviously, therefore, an 
80 per cent, product from a wheat of this type would contain con- 
siderably more " offal " than an 80 per cent, product from a larger 
grained wheat, which would yield about 70 per cent, of ordinary 
flour. 

With a view to overcoming this difficulty it has been suggested 
that reference to the proportion which the flour should bear to the 
original wheat should be omitted from a definition, and that a 
standard of fibre content of flour should be prescribed instead. 
Wheat contains on an average about 2*5 per cent, of fibre*, butthe 
amount is variable. In ordinary flour the amount should be less 
than 05 per cent. In prescribing a definition in terms of fibre 
content for the class of flour now commonly known as " standard," 
a value for the fibre content intermediate between those given 
above would have to be fixed. The ratio which flour conforming 
with this standard would bear to the whole wheat grain from which 
it was milled, would, however, vary with the size of the grain. 
Moreover, a standard based on fibre content would not enable a 
" straight-run " flour, containing the necessary amount of offal 
and, therefore, of fibre, to be distinguished from a low grade flour 
to which the requisite amount of offal had been added. The 

* This term includes a group of allied substances such as celluloses, pentosans 
and lignin, which enter into the formation of the woody fibre of plants. 



44 

accurate estimation of fibre also presents difficulties. Fibre is 
not an entity, but is an organic complex, and the methods 
employed in its estimation are somewhat empirical and arbitrary. 
In many cases no useful deduction as to the nature of the flour 
could be drawn from its estimation. 

It has further been suggested that so-called " standard " flour 
should be defined in terms of its mineral content. A criterion of 
this kind also presents difficulties. Flour which complied with a 
standard as regards ash may have had its mineral content raised by 
the addition of suitable but undesirable inorganic salts. 

In general, it may be said that the great practical difficulty 
in endeavouring to define any one variety of flour (whole- 
meal, " standard," or other) in terms of protein content, mineral 
content, or other physico-chemical criteria, is that such 
a definition to be effective would require a preliminary standard- 
isation of wheat. In present circumstances such standardisation 
is impracticable ; the wheat supply of this country is necessarily 
drawn from many separate sources, and is grown in a variety of 
circumstances which influence the character and composition of the 
grain. An endeavour to obtain uniformity by prescription of 
physico-chemical limits, sufficiently stringent to be of value, would 
inevitably rule out a considerable portion of the wheat at present 
imported.* 

It should be understood that the above paragraphs relate to the 
impracticability of defining " standard " flour in a way which 
would ensure a product of uniform composition being supplied 
under that name. It is obvious, however, that there may be par- 
ticular instances in which neither the trade expert nor the analyst 
need have any difficulty in pronouncing that a flour is so different 
from any flour of the ' ' standard ' ' class that it cannot properly be 
termed " standard " flour, and similarly with " standard " bread. 
Chemical analysis in regard to fibre, mineral matter, &c, may, 
of course, be of great value in cases where it is desired to know if 
the flour supplied complies with a given specification or corres- 
ponds to sample, and the utility of analysis for this purpose is 

* Reference may in this connection be made to the definitions and standards 
for the various classes of flours obtained from wheat which have been pre- 
scribe! by the United States Department of Agriculture and by the Canadian 
Government and those which have been recommended by the Departmental 
Conference on uniform standards for food and drugs in the Commonwealth and 
States of Australia to be applied throughout the Commonwealth. To the 
extent that these definitions apply to methods of preparation and prohibit the 
addition of foreign matter to flour they appear of considerable practical utility. 
So far as different classes of genuine flour are concerned, however, the limits 
prescribed (except in the case of moisture) are so wide in their scope as to admit 
flours of very different characters, and on this account appear of little use in 
securing uniformity in the article defined. 

Much can be said, however, in favour of a maximum limit for the water con- 
tent of flour. In the United States and in Canada this limit is 13*5 per cent., 
and the same limit is recommended for the Commonwealth of Australia. 
Excessive moisture in flour impairs its keeping qualities. From a nutritive 
point of view also the consumer is prejudiced when a stage is reached at which 
he is buying unnecessary water instead of flour. A flour factor informed me 
that the flour which he purchases may contain as much as 18 per cent, of water, 
and a sack of flour (280 lbs.) on being kept for a month or so may lose as much 
as 10 pounds in weight. 



45 

likely to increase with tHe attention which is now being given to 
the matter by chemists. 

" Standard " flour belongs to the class of " entire " wheat 
flours, and the observations made earlier in this report regarding 
the chemical composition and relative value in nutrition of 
" entire " wheat flour are applicable to " standard " flour. 

It is not to be expected that an " imitation standard " flour, or 
bread made therefrom, need show any conspicuous difference in 
chemical composition from genuine " standard " varieties. The 
description above given shows that it is practicable to prepare 
" standard " and " imitation standard " flours, which, in most 
respects are very similar. Such differences as exist in practice 
result in the main from the exclusion of the patent grade flour in 
the case of " imitation standard," or to the effect of mixing a 
" household " grade of flour obtained from one wheat with the 
germ and offal obtained from wheat of another class. There is 
not much to choose between the two varieties as regards the pro- 
portion of protein and mineral matter. So far as protein is con- 
cerned, there is likely, as a rule, to be more in an " imitation 
standard " flour, since in this the patent grades which are the 
poorest in protein have been removed. The differences which 
exist between " standard " and " imitation standard ' flour 
would, of course, be accentuated by the presence of an unduly 
large proportion of offal in the latter. 

TTith regard to the value of " standard " and " imitation 
standard ' ' bread in nutrition, it will suffice here to refer to the 
particulars given above respecting " entire " wheat flour and 
bread made therefrom. It would seem that " standard " flour 
(regarded as an 80 per cent, straight-run, together with the germ) 
has advantages over the " imitation standard " in the palatability 
and appearance of the loaf made from it, and I have already 
emphasised the importance of these considerations in connection 
with questions of food value. These advantages are partly due 
to the method of preparation, and also in the case of stone-milled 
flour, to the large proportion of English wheat which is generally 
used, the flavour of which is good. 

For any serviceable comparison to be made between the com- 
position of " standard ' flour and other varieties, such as 
" patents," " households," or wholemeal, it is necessary that the 
flours examined should be milled from the same wheat or wheat 
mixture. Erroneous inferences have been drawn in consequence 
of neglect of this principle. 

By the courtesy of several millers I have been able to secure 
samples of various flours and milling products obtained from 
different wheat mixtures. The samples have been analysed by my 
colleague, Dr. G. W. Monier- Williams, at the Board's Chemical 
Laboratory. The analyses of the products from each particular 
wheat mixture have been grouped together, and are set out in 
Table 21, which shows the composition of ' 80 per cent." or 
" standard " flour in relation to other milling products obtained 
from seven different wheat mixtures. It will be seen that the 
differences in protein and mineral matter between the ''standard " 
(80 per cent.) flours and the household flours obtained from the 
same wheat are comparatively small in each series. 



46 



Table 21. 

Analyses of samples of various flours and other milling products 
obtained from different wheat mixtures. 






Approx. 

percent^ 
age on 
wheat. 


Moisture. 


Ash. 


Phos- 
phoric 
acid 

(P 2 5 ). 


Proteins 
(N X 5-7). 


Ether 
extract. 




r Wholemeal 

Patent flour 

Household flour ... 

Germ 

Middlings (sharps) 

Bran, &c 

80°/ flour 

Middlings (sharps), 

coarse. 
^Bran, &c 


100 


13-30 


1-45 


0-67 


11-00 


1-88 


< 

U 

-+= 


37 

37 
0-3 
9-3 

16-4 


13-81 
14-15 
12-74 
12-35 


0-38 
0-59 
3-94 
3-14 


0-17 
0'27 
2-19 
1-65 


9-97 
10-43 
23-94 
16-25 


1-01 
1-28 
8-12 
5-00 


100 




A 
£ 


81 
2-5 

16-5 


13-80 
12-04 


0-69 
3-89 


0-31 
1-94 


10-20 
14-14 


1-41 
4-83 




100 




m 

t-t 


''Patent flour 
Household flour ... 
Bran, pollards, and 
middlings (sharps). 

80°/ o flour 

Bran, pollards, and 
c middlings (sharps). 


42 
28 
30 


14-57 
14-14 


0-35 
0-59 


0-17 
0-27 


10-83 
11-99 


1-00 
1-60 


a* 

-+3 


100 




.a 


80 
20 


14-43 


0-68 


0-35 


11-80 


1-62 




100 






r Patent flour 
Household flour ... 
Middlings (sharps) 
Bran, &c. ... 

80°/ o flour 

Middlings (sharps), 

coarse. 
Bran 

Straight-run flour 
Middlings (sharps) 
^Bran 


35 
35 
14 
16 


11-54 
11-59 
10-54 
10-68 


0-41 
0-59 
3-79 
4-65 


0-20 
0-25 
1-71 
2-31 


10-54 
11-34 
16-53 
14-65 


1-13 
1-21 
4-65 
3-51 




100 




3 
H 

a^ 

o3 
<D 
,4 


80 
4 

16 


11-60 
10-34 

10-68 


0-75 
3-90 

4-65 


0-36 
1-99 

2-31 


11-63 
16-36 

14-65 


1-45 

4-81 

3-51 


£ 


100 






70 
14 
16 


11-53 
10-54 

10-68 


0-51 

3-79 
4-65 


0-22 
1-71 
2-31 


11-17 
16-53 
1465 


1-13 
4-65 
3-51 




100 





47 



Table 21. — continued. 



Approx. 

percent- 
age on 
wheat. 



Moisture. 



Ash. 



Phos- 
phoric 
acid 

(PA)- 



Proteins 
(N X 5'7j 



Ether 
extract. 



© 

.a j 

! 



f Patent flour 
"Whites "flour ... 
Household flour ... 
Germ 
Pollards and 

middlings (sharps). 
Bran 



80°/ o flour 

Middlings (sharps), 

coarse. 
Bran 



© 

M 






f Patent flour 
Household flour ... 
Germ 

Middlings (sharps) 
Bran 



80°/ o flour 

Middlings (sharps), 

coarse. 
Bran 



PB| 



53 

-t-= 



11 



Wholemeal (stone 
ground). 

Patent flour 
Household flour ... 
Middlings (sharps) 
Bran and pollards... 



o 



Straight-run 
Middlings (sharps) 
te Bran and pollards 



23 
23 
23 

0-5 
20 

10-5 



100 



15-15 
15-12 
14-66 
14-70 
14-44 

15-32 



80 
9-5 

10-5 



100 



15-21 
15-47 

15-32 



0-36 
0-41 
0-55 
4-25 
3-45 

5-08 



0-61 
4-20 

5-08 



0-16 
0-19 
0-26 
2-38 
1-54 

2-69 



0-30 
2-02 

2-69 



18 
53 
0-5 
13-5 
15 



100 



80-5 
4-5 

15 



100 



100 



25-5 
44-5 
11-5 
18-5 



100 



70 

11-5 

18-5 

100 



13-97 



14-33 
14-34 
13-71 
14-45 



14-27 

13-71 
14-45 



1-54 



0-35 
0-50 
312 
4-54 



0-79 



0-18 
0-24 
1-68 
2-41 



0-43 
3-12 
4-54 



0-21 
1-68 
2-41 



1037 
10-54 
11-34 
28-10 
14-59 

13-22 



11-17 
14-36 

13-22 



13-42 


036 


0-19 


11-17 


12-28 


0-51 


0-28 


12-43 


10-64 


3-76 


2-07 


25-54 


12-07 


334 


1-74 


15-33 


13-72 


4-78 


2-52 


14-02 


12-35 


0-78 


0-41 


12-43 


12-54 


4-14 


2-13 


15-50 


13-72 


4-78 


2-52 


14-02 



12-60 



10-37 
11-51 
16-30 
1550 



11-00 
16-30 
15-50 



0-89 
0-93 
1-22 

8-71 
3-86 

2-82 



1-40 
4-00 

2-82 



111 
1-32 
7-53 
4-01 
3-98 



1-42 
4-54 

3-98 



1-84 



0-70 
1-06 
4-01 
313 



1-04 
401 
313 



48 



Table 21. — continued. 






Approx. 

percent- 
age on 
wheat. 


Moisture. 


Ash. 


Phos- 
phoric 
acid 

(PA)- 


Proteins 
(N X 5-7). 


Ether 
extract. 


© 
1 


r 80°/ o stone -milled 
Middlings (sharps), 

coarse. 
Pollards 
Bran 

Stone-milled flour... 

Bran, pollards, and 

k middlings (sharps). 


80-5 
4 

6-5 
9 


14-24 
14-30 

13-34 
14-19 


0-66 
2-61 

4-00 
4-77 


0-31 
1-36 

2-07 
2-56 


11-34 
14-19 

15-33 
14-99 


1-21 
3-93 

3-61 

2-40 


100 




■4= 

is 


74 

26 


14-18 


0-56 


0-25 


10-54 


0-85 




100 




3 


'Patent flour 
Household flour ... 

Middlings 

Pollards 

Bran 

80°/ o flour 

Middlings 

Pollards 

Bran 

Straight run 
Bran, pollards, and 
^ middlings. 


20 
49-5 
13 
9-5 

8 


14-27 
14-63 
13-92 

13-92 
14-10 


0-37 
0-50 
2-36 
4-63 
5-86 


0-18 
0-24 
1-34 
•2-52 
3-15 


8-61 

9-12 

13-22 

12-60 

12-14 


0-86 
1-07 
3-79 
4-33 
3-58 


100 






80 
25 
9-5 

8 


14-50 
14-14 
13-92 
14-10 


0-74 
2-15 
4-63 
5-86 


0-38 
1-17 
2-52 
3-15 


9-92 
10-54 
12-60 
12-14 


1-45 
2-91 
4-38 
3-58 


100 






69-5 
20-5 


14-71 


0-51 


0-20 


9-12 


0-98 






100 





IV.— GEKEKAL REVIEW. 

The records of experimental work which have been consulted 
for the purposes of this report, and other writings on the subject, 
do not permit any conclusive statements to be made regarding the 
exact relative value in nutrition of different varieties of flour. 
Although many of the researches, particularly those carried out 
for the United States Department of Agriculture, have been 
undertaken on a large and elaborate scale, there remain numerous 
points of uncertainty, while any inferences which may now be 
drawn from observed facts are necessarily liable to require con- 
siderable modification as knowledge of the physiology and 
chemistry of nutrition advances. It is, however, permissible to 
conclude this report by some general observations on the practical 
aspect of the question, as it at present appears. 



49 

To begin with, the differences in nature and in nutritive value 
between breads made from the different classes of Hour, described 
on pp. 11 and 12, do not appear to be of much importance to the 
average adult with whom bread is only one out of many varied 
constituents of his dietary. The notion, for example, that 
ordinary high grade and naturally white " patent " flour is prac- 
tically devoid of protein or nitrogenous constituents, whereas the 
latter are abundantly present in bread made from wholemeal and 
" entire " wheat flours is erroneous. The differences which exist 
in this respect are not relatively of great magnitude, and they 
may, to a large extent, be neutralised by imperfect absorption 
from the digestive tract. Apart from this, there are commonly 
wider differences in protein content and energy value between 
" patent " flours obtained from different wheats, than between the 
" patent " flour of a given wheat and the corresponding whole- 
meal. In other words, a " patent ' flour obtained from one 
variety of wheat may contain considerably more total protein, 
and furnish more available energy than an " entire " wheat or 
wholemeal flour from another kind of wheat. 

Relatively marked differences exist between different classes of 
flour, even when derived from the same wheat, in regard to their 
total mineral content or those substances which are represented 
by mineral matter in the ash. To the average adult living on a 
reasonably liberal and varied diet, however, these differences 
cannot ordinarily be of importance. 

At the same time there is no doubt that some people who are 
accustomed to a mixed diet find, as a result of sufficient trial, 
that bread of one particular class — from " patent," " entire " 
wheat, wholemeal, or '* germ " flour — suits them, individually, 
better than another. Suitability in this sense may be the result 
of the greater or less time required for mastication ; the presence 
or absence of laxative properties ; the advantage or the reverse of 
including in the diet an article which leaves a larger undigested 
residue ; the nature of the other ordinary constituents of the 
dietary; differences in flavour, or other factors. Xo general rule 
can be laid down in such cases. The commercial supply of breads 
of all these classes serves a useful purpose by enabling a choice to 
be made. 

If now the question be asked what variety of flour is best suited 
for the diet of those adults whose food consists principally of 
bread, it should in the first place be answered that a diet which 
consists principally of bread, from whatever grade of flour it 
may be made, is unsatisfactory, and that it is more important 
for those who for one reason or another are in this position, to 
secure a greater variety of diet — which does not always 
mean greater cost — than to rely upon the selection of 
any particular form of bread, however nutritious. This 
being premised, it may be said that there is no reason to con- 
sider that the varieties of bread which the miller and baker have 
accustomed us to regard as of lower quality — " households," for 
example — are in any physiological sense inferior to that of the 
higher priced bread made from high grade and specially white 
flour. On the contrary, from the point of view of available 

20420 D 



60 

nutrient material and energy value, the advantage is on the side of 
the " households." 

" Entire ' wheat flours (including stone-ground Hours and 
" standard " flour) are in nearly the same position as " house- 
holds/' although when made from weak wheats they will usually 
contain less available protein than " households ' made from 
strong wheats. They possess, however, additional constituents, 
due to the presence of branny particles and the germ of the wheat, 
which appear to have a value of their own in nutrition, and may, 
as a result of further investigation, be shown to comprise phos- 
phorus-containing organic compounds or other substances, the 
presence of which in some part of the dietary, even in minute 
quantity, is important in maintaining good health. 

The latter consideration applies also to wholemeal flour, and to 
" germ " flours. It is probable, however, that the comparative 
coarseness of bread made from the former, and its liability to pro- 
duce digestive disturbances, would influence most people 
against its habitual adoption as a staple food. This objection does 
not apply to breads made from (l germ " flours, but these are, 
essentially, proprietary articles, and as their cost is distinctly 
greater than " household ' or " standard ' bread, those who 
have closely to consider the price of their bread might obtain 
better value, in respect of nutrition, by applying the difference in 
cost to the purchase of other food. 

It is asserted that wholemeal bread, and to a less extent bread 
made from flours of the " entire " wheat class are not so liable 
to aid the production of caries of the teeth, as a result of fermen- 
tative changes, as is bread made from a highly refined flour such 
as patent grade flour. The evidence on this point, however, can- 
not be considered conclusive in the absence of more exact 
experiment. 

As to the choice of bread for children, the same considerations as 
to the dominating importance of a varied diet apply. For those, 
however, who live largely on bread, or bread supplemented only 
by jam, sugar, or other foods which add little to the available 
mineral matter, proteins, organically-combined phosphorus, or 
other substances which possibly may be necessary for health, 
there appears, on the balance, to be advantage in the use of bread 
made from flour of the " entire " wheat class, or from wholemeal 
in which the bran is very finely ground. In these flours the 
presence of the offal, including the germ, secures a somewhat 
larger quantity of mineral matter and of suitably combined phos- 
phorus or other substances as yet unknown, which may 
prove In be of importance for reasons above indicated. 
II should, however, he remembered (hat many children 
whose food consists largely of bread, do noi gel enough 
of it, and are really underfed in respect o! such essential nutritive 
substances as proteins ami carbohydrates. To increase the 
quantity of bread taken in such cases may be of greater impor- 
tance than the substitution of one form of bread for another; to 
supplement the bread by other articles (such as milk) which con- 
tain ;i materia] quantity of protein, mineral matter, and organi- 
cally-combined phosphorus, will he ^till inei,' useful 

J. M. HAMILL. 



5) 

REFERENCES. 

1. Abderhalden, E. Lehrbuch der physiologischen Chemie. 

Urban and Schwarzenberg, lierlin, 1906. p. 399. 

2. Albu, H., and Neubekg, C. Mineralstoffwechsel. Julius 

Springer, Berlin, 190(3. p. 113. 

3. Bertz, F. Maly's Jahresbericht fur Tierchemie. 30. 

p. 457. 

4. Bessy, C. E. Bull. Agric. Expt. Stat. Nebraska. No. 32. 

p. 111. 

5. Blauberg, M. Zeitschrift fur Biologic. 40. p. 51. 

6. Camerer, W. Zeitscjirift fill' Biologic 43. p. 1. 

7. Edie, E. S., and Simpson, G. C. E. British Medical Journal. 

13th May, 1911, p. 1151, and 17th June, 1911, p. 1421. 

8. Ehrstrom, R. Skandin. Archiv fur Physiologic 14. 

p. 82. 

9. Fiskler, D. Zentralbl. f. allgemein. Gesundheitspft. 29. 

p. 241; and Journ. Roy. Inst. Pub. Health. 19. p. 
193. 

10. Eraser, H., and Stanton, A. T. Lancet, 17th Dec, 1910. 

p. 1755. 

11. Gabriel, S. Zeitschr. f. Anal. Chemie. 31. p. 522. 

12. Girard, A. Comptes Rendus de V Acad. Sci. 124. p. 876. 

13. Goodfellow, J. Dietetic Value of Bread. Macniillan and 

Co. 1892. 

14. Gumpert, E. Med. Klinik. 1. p. 1037. 

15. Harms, H. Zeitschr. f. Biol. 38. p. 487. 

16. Hart, E.B., and Andrews, W. H. Am. Chem. Journ. 30. 

p. 470. 

17. Hart, E.B., McCollum, E. V., and Fuller, J. G. American 

Journ. Physiol. 23. p. 246. 

18. Hempel, W., and Scheffler, W. Zeitschr. f. anorg. 

Chemie. 20. p. 1. 

19. Hill, L. British Medical Journal. 6th May, 1911. 

p. 1068. 

20. Hill, L., and Flack, M. British Medical Journal. 3rd 

June, 1911. p. 1310. 

21. Holsti, O. Skandin. Archiu filr Physiologic 23. p. 143. 

22. Ingle, H. Journal Agric. Science. 3. p. 22. 

23. Jodlbauer. Zcitsclir . f. Biologic 41. p. 487; and 44. 

p. 259. 

24. Lipschutz, A. Arcltiv filr exp. Path, und Pharm. 62. 

p. 210. 

25. Michel, A. Deutsche Monatschr. f. Zalinlieilk. 15. 

p. 332. 

26. Moeller, J. Zeitschrift filr Biologie. 35. p. 291. 

27. Neuberg, C. Biochem. Zeitschr. 9. p. 557. 

28. Oberndorffer, E. Berliner Klinische Wochensclirift. 

1904. p. 1068. 

29. Osborne, T. B., and Voorhees, C. G. Am. Chem. Joum. 

15. p. 392. 

30. Patten, A. J., and Hart, E. B. Am. Chem. Journ. 31. 

p. 564. 

31. Posternak, S. Comptes Rendus de VAcad. Sci. 137 

p. 202. 



o'2 

32. Pannwitz, K. Der Nahrwerth des Soldatenbrotes. Carl 

Hymann, Berlin, 1898. 

33. Renvall, G. Skandin. Archiv fur Physiologie. 16. 

p. 94. 

34. Romberg, E. Archiv. f. Hygiene. 28. p. 244. 

35. Rogozinski, F. Bull. Intemat. de V Acad. Sci. Cracovie, 

1910, No. 4B. p. 260. 

36. Rosenheim, 0., and Schidrowitz, P. Analyst. 24. 

p. 227. 

37. Rubner, M. Zeitschrift fur Biologie. 15. p. 115. 

38. Rubner, M. Zeitschrift fur Biologie. 19. p. 45. 

39. Rubner, M., and Heubner, 0. Zeitschrift fur Biologie. 36. 

p. 42. 

40. Schaumann, H. Beihefte zum Archiv f. Schiffs- und Tro pen- 

hygiene. 14. Beiheft 8. 

41. Siven, Y. Skandin. Archiv fur Physiologie. 11. p. 308. 

42. T amman, G. Zeitschr. f. Physiol. Chemie. 12. p. 322. 

43. U.S. Department of Agriculture (Division of Chemistry). 

Bulletin 13. Part 9. p. 1186. 

44. Ibid. p. 1189. 

45. Ibid. p. 1191. 

46. Ibid. p. 1212. 

47. Ibid. p. 1228. 

48. Ibid. p. 1323. 

49. U.S. Department of Agriculture (Office of Experiment 

Stations). Bulletin 21. p. 33. 

50. Ibid. p. 212. 

51. U.S. Department of Agriculture (Office of Experiment 

Stations). Bulletin 52. p. 46. 

52. U.S. Department of Agriculture (Office of Experiment 

Stations). Bulletin 67. p. 36. 

53. U.S. Department of Agriculture (Office of Experiment 

Stations). Bulletin 85. p. 42. 

54. U.S. Department of Agriculture (Office of Experiment 

Stations). Bulletin 101. p. 7. 

55. Ibid. p. 9. 

56. Ibid. p. 10. 

57. Ibid. p. 18. 

58. Ibid. p. 33. 

59. Ibid. p. 35. 

60. Ibid. p. 55. 

61. Ibid. p. 63. 

62. U.S. Department of Agriculture (Office of Experiment 

Stations). Bulletin 126. 

63. Ibid. p. 13. 

64. Ibid. p. 14. 

65. Ibid. p. 15. 

66. Ibid. p. 29. 

67. Ibid. p. 30. 

68. Ibid. p. 46. 

69. U.S. Department of Agriculture (Office of Experiment 

Stations). Bulletin 156. 

70. Ibid. p. 14. 



53 



Experiment 
Experiment 
May, 1911. 



71. Ibid. p. 15. 

72. Ibid. p. 37. 

73. Ibid. p. 43. 

74. Ibid. p. 44. 

75. Ibid. p. 50. 

76. U.S. Department of Agriculture (Office of 

Stations). Bulletin 185. 

77. U.S. Department of Agriculture (Office of 

Stations). Bulletin 227. 

78. Watson, C. British Medical Journal. 13th 

p. 1151. 

79. Wilcock, E. G., and Hopkins, F. G. Journal of Physio- 

logy. 35. p. 88. 

80. Wilson, G. Edin. Phil. Journ. 53. p. 356. 

81. Wynter Blyth, A. Proceedings of the Royal Society. 45. 

p. 549. 

82. Wrampelmeyer, E. Zeitschr. f. Anal. Chew. 32. p. 550. 

83. Zdarek, E. Zeitschr. f. Physiol. Chem. 69. p. 127. 

References to other work bearing on the nutritive value of bread 
will be found in many of the above publications. 



20420 



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REPORTS 



TO THE 




014 338 894 3 

LOCAL GOVERNMENT BOARD 



ON 



PUBLIC HEALTH AND MEDICAL 

SUBJECTS. 

(NEW SERIES No. 55.) 



Dr. J. M. HamiU's Report to the Local Govern- 
ment Board on the nutritive value of bread 
made from different varieties of wheat flour. 

[Food Reports, No. 14.] 



Presented So boil) Houses of Parliament by Command of Hss fttaiesty 




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